Regular expression to match numbers with or without commas and decimals in text

Question

I m trying to locate and replace all numbers in a body of text   I ve found a few example regex s  which almost solve the problem  but none are perfect yet   The problem I have is that the numbers in my text may or may not have decimals and commas   For example       The 5000 lb  fox jumped over a 99 999 99998713 foot fence      The regex should return  5000  and  99 999 99998713    Examples I ve found break-up the numbers on the comma or are limited to two decimal places   I m starting to understand regex s enough to see why some examples are limited to two decimal places  but I haven t yet learned how to overcome it and also include the comma to get the entire sequence   Here is my latest version     0-9      0-9  0-9       Which returns   5000    99 99    9 99   and  998713  for the above text

User · Answer

d    d       d      This assumes that there is always at least one digit before or after any comma or decimal and also assumes that there is at most one decimal and that all the commas precede the decimal

User · Answer

Some days ago  I worked on the problem of removing trailing zeros from the string of a number   In the continuity of that problem  I find this one interesting because it widens the problem to numbers comprising commas   I have taken the regex s pattern I had writen in that previous  problem I worked on and I improved it in order that it can treat the numbers with commas as an answer for this problem    I ve been carried away with my enthusiasm and my liking of regexes  I don t know if the result fits exactly to the need  expressed by Michael Prescott  I would be interested to know the points that are in excess or in lack in my regex  and to correct it to make it more suitable for you   Now  after a long session of work on this regex  I have a sort of weight in the brain  so I m not fresh enough to give a lot of explanation  If points are obscure  and if anybody may come to be interested enough   please  ask me   The regex is built in order that it can detect the numbers expressed in scientific notation 2E10 or even 5 22 454 12E-00 0478   removing unnecessary zeros in the two parts of such numbers too  If an exponent is equal to zero   the number is modified so that there is no more exponent   I put some verification in the pattern so that some particular cases will not match  for exemple  12  57  won t match  But in   111  the string  111  matches because the preceding comma is considered a comma not being in a number but a comma of sentence   I think that the managing of commas should be improved  because it seems to me that there are only 2 digits between commas in Indian numbering  It won t be dificult to correct  I presume  Here after is a code demonstrating how my regex works  There are two functions  according if one wants the numbers   1245  to be transformed in  0 1245  or not   I wouldn t be surprised if errors or unwanted matchings or unmatchings will remain for certain cases of number strings  then I d like to know these cases to understand and correct the deficiency   I apologize for this code written in Python  but regexes are trans-langage and I think everybody will be capable of undertsanding the reex s pattern  import re  regx   re compile     lt    d              lt    d   eE   -     lt    d   eE     lt   d                             ---------------------------------                       -                             d        d        d                             0     0     lt   d                                                      d      1-9        d                                  0                           lt        d                            d      d                         0                         ---------------------------------                                              eE   -      0     0                                                   0     D  Z       d      1-9        d                                   lt          0     D  Z   d                            d        0     D  Z   d                         0                                                ---------------------------------                             d      def dzs numbs x regx   regx     ds   detect and zeros-shave     if not regx findall x           yield   No match     No catched string     No groups        for mat in regx finditer x           yield  mat group       join mat groups       mat groups       def dzs numbs2 x regx   regx     ds   detect and zeros-shave     if not regx findall x           yield   No match     No catched string     No groups        for mat in regx finditer x           yield  mat group                      join   0  if n startswith      else     n for n in mat groups                      mat groups       NS       23456000and23456000  or23456000 000  00023456000 s000023456000   000023456000 000           arf 10000 sea10000  10000 000  00010000-00010000  kant00010000 000             24   24   24    24 000  24 000    00024r 00024  blue 00024 000              8zoom8   8 000  0008  0008  and0008 000              0   00000M0    000   0 0  0 000    000 0   000 000    000000    0                0000023456     0000023456000               0005872     0005872000    00503    00503000                068     0680000    8    8000   123456123456     123456123456000                 657    657000    45     4500000    7     70000  0 0000023230000   000 0000023230000               0 0081000    0000 0081000  0 059000   0000 059000                 0 78987400000 snow  00000 78987400000  0 4400000   00000 4400000               -0 5000  -0000 5000   0 90   000 90   0 7   000 7               2 6    00002 6   00002 60000  4 71   0004 71    0004 7100               23 49   00023 49   00023 490000  103 45   0000103 45   0000103 45000                10003 45067   000010003 45067   000010003 4506700              15000 0012    000015000 0012    000015000 0012000                78000 89   000078000 89   000078000 89000                 0457e10    0457000e10   00000 0457000e10               258e8   2580000e4   0000000002580000e4               0 782e10   0000 782e10   0000 7820000e10              1 23E2   0001 23E2  0001 2300000E2               432e-102  0000432e-102   004320000e-106               1 46e10and0001 46e10  0001 4600000e10               1 077e-300  0001 077e-300  0001 077000e-300               1 069e10   0001 069e10   0001 069000e10               105040 03e10  000105040 03e10  105040 0300e10                 286E000024 487900  -78 4500e 14500    0140E789               081 12 40E07 95 0120     0045 78 123 03500e-0 00              0096 78 473 0380e-0     0008 78 373 066000E0     0004512300 E0000                18000  25  00 36   77   2  8              3 8  9     12500      12 51 400              00099 111 8713000   -0012 45 83 987 26 0 000 099 88 44 or00 00 00 00must            00099 44 and   0000 099 88 44 bom          00 000 00 587000  77 98 23 45    this that              111  145 20   9 9 9  0012800        1  100 000           1 1 1 111  000 001 111   -999   0   111 110000  1 1 1 111  9 909 888     for ch in NS      print  string    repr ch      for strmatch  modified  the groups in dzs numbs2 ch           print strmatch rjust 20     modified    the groups     print   result  string     23456000and23456000  or23456000 000  00023456000 s000023456000   000023456000 000               23456000  23456000        23456000                                          23456000   23456000        23456000                                       23456000 000  23456000        23456000                                        00023456000  23456000        23456000                                      000023456000   23456000        23456000                                   000023456000 000  23456000        23456000                                string   arf 10000 sea10000  10000 000  00010000-00010000  kant00010000 000                  10000  10000        10000                                             10000   10000        10000                                          10000 000  10000        10000                                           00010000  10000        10000                                          00010000   10000        10000                                       00010000 000  10000        10000                                string     24   24   24    24 000  24 000    00024r 00024  blue 00024 000                      24  24        24                                                24   24        24                                                24   24        24                                             24 000  24        24                                             24 000  24        24                                              00024  24        24                                             00024   24        24                                          00024 000  24        24                                string     8zoom8   8 000  0008  0008  and0008 000                       8  8        8                                                 8   8        8                                              8 000  8        8                                               0008  8        8                                              0008   8        8                                           0008 000  8        8                                string     0   00000M0    000   0 0  0 000    000 0   000 000    000000    0                        0  0        0                                              00000  0        0                                                 0   0        0                                               000   0        0                                                0 0  0            0                                          0 000  0            0                                          000 0  0            0                                        000 000  0            0                                         000000  0            0                                              0  0            0                            string      0000023456     0000023456000      0005872     0005872000    00503    00503000               0000023456  0 0000023456                 0000023456                              0000023456000  0 0000023456                 0000023456                                    0005872  0 0005872                 0005872                                 0005872000  0 0005872                 0005872                                      00503  0 00503                 00503                                   00503000  0 00503                 00503                        string      068     0680000    8    8000   123456123456     123456123456000                       068  0 068                 068                                    0680000  0 068                 068                                          8  0 8                 8                                       8000  0 8                 8                               123456123456  0 123456123456                 123456123456                            123456123456000  0 123456123456                 123456123456                        string      657    657000    45     4500000    7     70000  0 0000023230000   000 0000023230000                      657  0 657                 657                                     657000  0 657                 657                                         45  0 45                 45                                    4500000  0 45                 45                                          7  0 7                 7                                      70000  0 7                 7                            0 0000023230000  0 000002323                 000002323                          000 0000023230000  0 000002323                 000002323                        string     0 0081000    0000 0081000  0 059000   0000 059000                  0 0081000  0 0081                 0081                               0000 0081000  0 0081                 0081                                   0 059000  0 059                 059                                0000 059000  0 059                 059                        string     0 78987400000 snow  00000 78987400000  0 4400000   00000 4400000            0 78987400000  0 789874                 789874                          00000 78987400000  0 789874                 789874                                  0 4400000  0 44                 44                              00000 4400000  0 44                 44                        string     -0 5000  -0000 5000   0 90   000 90   0 7   000 7                  -0 5000  -0 5    -             5                                 -0000 5000  -0 5    -             5                                       0 90  0 9                 9                                     000 90  0 9                 9                                        0 7  0 7                 7                                      000 7  0 7                 7                        string     2 6    00002 6   00002 60000  4 71   0004 71    0004 7100                      2 6  2 6                    2 6                                00002 6  2 6                    2 6                            00002 60000  2 6                    2 6                                   4 71  4 71                    4 71                                0004 71  4 71                    4 71                              0004 7100  4 71                    4 71                    string     23 49   00023 49   00023 490000  103 45   0000103 45   0000103 45000                     23 49  23 49                    23 49                               00023 49  23 49                    23 49                           00023 490000  23 49                    23 49                                 103 45  103 45                    103 45                             0000103 45  103 45                    103 45                          0000103 45000  103 45                    103 45                    string     10003 45067   000010003 45067   000010003 4506700            10003 45067  10003 45067                    10003 45067                        000010003 45067  10003 45067                    10003 45067                      000010003 4506700  10003 45067                    10003 45067                    string      15000 0012    000015000 0012    000015000 0012000                15000 0012   15000 0012                     15000 0012                         000015000 0012   15000 0012                     15000 0012                      000015000 0012000   15000 0012                     15000 0012                    string     78000 89   000078000 89   000078000 89000                  78000 89  78000 89                    78000 89                           000078000 89  78000 89                    78000 89                        000078000 89000  78000 89                    78000 89                    string      0457e10    0457000e10   00000 0457000e10                 0457e10  0 0457e10                 0457        e    10                     0457000e10  0 0457e10                 0457        e    10               00000 0457000e10  0 0457e10                 0457        e    10            string      258e8   2580000e4   0000000002580000e4                    258e8  258e8        258                e    8                      2580000e4  2580000e4        2580000                e    4             0000000002580000e4  2580000e4        2580000                e    4            string     0 782e10   0000 782e10   0000 7820000e10                0 782e10  0 782e10                 782        e    10                    0000 782e10  0 782e10                 782        e    10                0000 7820000e10  0 782e10                 782        e    10            string     1 23E2   0001 23E2  0001 2300000E2                   1 23E2  1 23E2                    1 23    E    2                      0001 23E2  1 23E2                    1 23    E    2                 0001 2300000E2  1 23E2                    1 23    E    2            string     432e-102  0000432e-102   004320000e-106                 432e-102  432e-102        432                e-    102                   0000432e-102  432e-102        432                e-    102                 004320000e-106  4320000e-106        4320000                e-    106            string     1 46e10and0001 46e10  0001 4600000e10                  1 46e10  1 46e10                    1 46    e    10                     0001 46e10  1 46e10                    1 46    e    10                0001 4600000e10  1 46e10                    1 46    e    10            string     1 077e-300  0001 077e-300  0001 077000e-300               1 077e-300  1 077e-300                    1 077    e-    300                  0001 077e-300  1 077e-300                    1 077    e-    300               0001 077000e-300  1 077e-300                    1 077    e-    300            string     1 069e10   0001 069e10   0001 069000e10                 1 069e10  1 069e10                    1 069    e    10                    0001 069e10  1 069e10                    1 069    e    10                 0001 069000e10  1 069e10                    1 069    e    10            string     105040 03e10  000105040 03e10  105040 0300e10              105040 03e10  105040 03e10                    105040 03    e    10                000105040 03e10  105040 03e10                    105040 03    e    10                 105040 0300e10  105040 03e10                    105040 03    e    10            string      286E000024 487900  -78 4500e 14500    0140E789        286E000024 487900   286E24 4879         286                E            24 4879        -78 4500e 14500  -78 45e0 145    -                78 45    e         145                  0140E789   0 014E789                 014        E    789            string     081 12 40E07 95 0120     0045 78 123 03500e-0 00    081 12 40E07 95 0120  81 12 4E7 95 012                    81 12 4    E            7 95 012      0045 78 123 03500  45 78 123 035                    45 78 123 035                    string     0096 78 473 0380e-0     0008 78 373 066000E0     0004512300 E0000        0096 78 473 0380  96 78 473 038                    96 78 473 038                     0008 78 373 066000  8 78 373 066                    8 78 373 066                            0004512300   4512300        4512300                                string       18000  25  00 36   77   2  8               No match   No catched string   No groups   string     3 8  9     12500      12 51 400               No match   No catched string   No groups   string     00099 111 8713000   -0012 45 83 987 26 0 000 099 88 44 or00 00 00 00must     00099 111 8713000  99 111 8713                    99 111 8713                     -0012 45 83 987 26  -12 45 83 987 26    -                12 45 83 987 26                            00 00 00 00  0            0                            string     00099 44 and   0000 099 88 44 bom             00099 44   99 44        99 44                                    0000 099 88 44   99 88 44        99 88 44                                string   00 000 00 587000  77 98 23 45    this that       00 000 00 587000  0 587                 587                               77 98 23 45   77 98 23 45        77 98 23 45                                string      111  145 20   9 9 9  0012800        1  100 000                    111  111        111                                             145 20  145 2                    145 2                                  9 9 9   9 9 9         9 9 9                                            0012800  12800        12800                                                  1  1        1                                            100 000  100 000        100 000                                string   1 1 1 111  000 001 111   -999   0   111 110000  1 1 1 111  9 909 888             1 1 1 111  1 1 1 111                    1 1 1 111                            000 001 111  1 111                    1 111                                  -999   -999    -    999                                                 0   0        0                                         111 110000  111 11                    111 11

User · Answer

Here s a regex       d     d 1 3           d 3        d      that accepts numbers    without spaces and or decimals  eg  123456789  123 123 with commas or spaces as thousands separator and or decimals  eg  123 456 789  123 456 789 100  123 456  3 232 300 000 00   Tests  http   regexr com 3h1a2

User · Answer

This regex     d 1 3   d 3    d 3        d     d     d    Matched every number in the string   1 1 0 0 1 1 001 1 000 1 000 000 1000 1 1 000 1 1 323 444 000 1 999 1 222 455 666 0 1 244

User · Answer

b d      b------- word boundary    d ------ one or digit   -------- containing commas   Eg   sddsgg 70 000 sdsfdsf fdgfdg70 00  sfsfsd 5 44 4343 5 7788 44 555   It will match   70   5   44    44

User · Answer

Taking a certain liberty with the requirements  you re looking for   d    d    d      d      But notice this will match e g  11 11 1

User · Answer

The regex below will match both numbers from your example      b d  d     b   It will return 5000 and 99 999 99998713 - matching your requirements

User · Answer

d      d       This would match any small or large number as following with or without comma  1 100 1 262 1 56 262 10 78 999 12 34 56 789   or  1 100 1262 156262 1078999 123456789

User · Answer

Here is another construction which starts with the simplest number format and then  in a non-overlapping way  progressively adds more complex number formats   Java regep     d    1-9  d       d     d   d     1-9  d    d     1-9  d 0 2    d 3       d       As a Java String  note the extra   needed to escape to   and   since   and   have special meaning in a regexp when on their own    String myregexp     d    1-9   d         d      d     d     1-9   d      d     1-9   d 0 2     d 3         d            Explanation    This regexp has the form A B C D E F where A B C D E F are themselves regexps that do not overlap  Generally  I find it easier to start with the simplest possible matches  A  If A misses matches you want  then create a B that is a minor modification of A and includes a bit more of what you want  Then  based on B  create a C that catches more  etc  I also find it easier to create regexps that don t overlap  it is easier to understand a regexp with 20 simple non-overlapping regexps connected with ORs rather than a few regexps with more complex matching  But  each to their own  A is   d  and matches exactly one of 0 1 2 3 4 5 6 7 8 9 which can t be simpler  B is   1-9  d   and only matches numbers with 2 or more digits  the first excluding 0   B matches exactly one of 10 11 12     B does not overlap A but is a small modification of A  C is    d   and only matches a decimal followed by one or more digits  C matches exactly one of  0  1  2  3  4  5  6  7  8  9  00  01  02        23000     C allows trailing eros on the right which I prefer  if this is measurement data  the number of trailing zeros indicates the level of precision  If you don t want the trailing zeros on the right  change    d   to    d  1-9   but this also excludes  0 which I think should be allowed  C is also a small modification of A  D is   d  d   which is A plus decimals with trailing zeros on the right  D only matches a single digit  followed by a decimal  followed by zero or more digits  D matches 0  0 0 0 1 0 2     0 01000   9  9 0 9 1  0 0230000         9 9999999999    If you want to exclude  0   then change D to   d  d    If you want to exclude trailing zeros on the right  change D to   d  d  1-9   but this excludes 2 0 which I think should be included  D does not overlap A B or C   E is   1-9  d   d   which is B plus decimals with trailing zeros on the right  If you want to exclude  13    for example  then change E to   1-9  d   d    E does not overlap A B C or D  E matches 10  10 0 10 0100       99 9999999999     Trailing zeros can be handled as in 4  and 5  F is   1-9  d 0 2    d 3      d     and only matches numbers with commas and possibly decimals allowing trailing zeros on the right  The first group   1-9  d 0 2   matches a non-zero digit followed zero  one or two more digits  The second group    d 3    matches a 4 character group  a comma followed by exactly three digits  and this group can match one or more times  no matches means no commas    Finally     d    matches nothing  or matches   by itself  or matches a decimal   followed by any number of digits  possibly none  Again  to exclude things like  1 111    change    d   to    d    Trailing zeros can be handled as in 4  or 5  F does not overlap A B C D  or E  I couldn t think of an easier regexp for F    Let me know if you are interested and I can edit above to handle the trailing zeros on the right as desired   Here is what matches regexp and what does not   0 1 02  lt - invalid 20 22 003  lt - invalid 030  lt - invalid 300 033  lt - invalid 303 330 333 0004  lt - invalid 0040  lt - invalid 0400  lt - invalid 4000 0044  lt - invalid 0404  lt - invalid 0440  lt - invalid 4004 4040 4400 0444  lt - invalid 4044 4404 4440 4444 00005  lt - invalid 00050  lt - invalid 00500  lt - invalid 05000  lt - invalid 50000 00055  lt - invalid 00505  lt - invalid 00550  lt - invalid 05050  lt - invalid 05500  lt - invalid 50500 55000 00555  lt - invalid 05055  lt - invalid 05505  lt - invalid 05550  lt - invalid 50550 55050 55500    lt - invalid     lt - invalid  0 0   1 1   00 0 0 00   lt - invalid  02 0 2 02   lt - invalid  20 2 0 20   22 2 2 22   000 0 00 00 0  lt - invalid 000   lt - invalid  003 0 03 00 3  lt - invalid 003   lt - invalid  030 0 30 03 0  lt - invalid 030   lt - invalid  033 0 33 03 3  lt - invalid 033   lt - invalid  303 3 03 30 3 303   333 3 33 33 3 333   0000 0 000 00 00  lt - invalid 000 0  lt - invalid 0000   lt - invalid  0004 0 0004 00 04  lt - invalid 000 4  lt - invalid 0004   lt - invalid  0044 0 044 00 44  lt - invalid 004 4  lt - invalid 0044   lt - invalid  0404 0 404 04 04  lt - invalid 040 4  lt - invalid 0404   lt - invalid  0444 0 444 04 44  lt - invalid 044 4  lt - invalid 0444   lt - invalid  4444 4 444 44 44 444 4 4444   00000 0 0000 00 000  lt - invalid 000 00  lt - invalid 0000 0  lt - invalid 00000   lt - invalid  00005 0 0005 00 005  lt - invalid 000 05  lt - invalid 0000 5  lt - invalid 00005   lt - invalid  00055 0 0055 00 055  lt - invalid 000 55  lt - invalid 0005 5  lt - invalid 00055   lt - invalid  00505 0 0505 00 505  lt - invalid 005 05  lt - invalid 0050 5  lt - invalid 00505   lt - invalid  00550 0 0550 00 550  lt - invalid 005 50  lt - invalid 0055 0  lt - invalid 00550   lt - invalid  05050 0 5050 05 050  lt - invalid 050 50  lt - invalid 0505 0  lt - invalid 05050   lt - invalid  05500 0 5500 05 500  lt - invalid 055 00  lt - invalid 0550 0  lt - invalid 05500   lt - invalid  50500 5 0500 50 500 505 00 5050 0 50500   55000 5 5000 55 000 550 00 5500 0 55000   00555 0 0555 00 555  lt - invalid 005 55  lt - invalid 0055 5  lt - invalid 00555   lt - invalid  05055 0 5055 05 055  lt - invalid 050 55  lt - invalid 0505 5  lt - invalid 05055   lt - invalid  05505 0 5505 05 505  lt - invalid 055 05  lt - invalid 0550 5  lt - invalid 05505   lt - invalid  05550 0 5550 05 550  lt - invalid 055 50  lt - invalid 0555 0  lt - invalid 05550   lt - invalid  50550 5 0550 50 550 505 50 5055 0 50550   55050 5 5050 55 050 550 50 5505 0 55050   55500 5 5500 55 500 555 00 5550 0 55500   05555 0 5555 05 555  lt - invalid 055 55  lt - invalid 0555 5  lt - invalid 05555   lt - invalid  50555 5 0555 50 555 505 55 5055 5 50555   55055 5 5055 55 055 550 55 5505 5 55055   55505 5 5505 55 505 555 05 5550 5 55505   55550 5 5550 55 550 555 50 5555 0 55550   55555 5 5555 55 555 555 55 5555 5 55555     lt - invalid     lt - invalid 1   lt - invalid  1  lt - invalid 22   lt - invalid 2 2  lt - invalid  22  lt - invalid 2 2   lt - invalid 2 2   lt - invalid  22   lt - invalid 333   lt - invalid 33 3  lt - invalid 3 33  lt - invalid  333  lt - invalid 3 33   lt - invalid 3 3 3  lt - invalid 3  33  lt - invalid   333  lt - invalid 4444   lt - invalid 444 4  lt - invalid 44 44  lt - invalid 4 444  4444  lt - invalid 55555   lt - invalid 5555 5  lt - invalid 555 55  lt - invalid 55 555 5 5555  lt - invalid  55555  lt - invalid 666666   lt - invalid 66666 6  lt - invalid 6666 66  lt - invalid 666 666 66 6666  lt - invalid 6 66666  lt - invalid 66 66 66  lt - invalid 6 66 666  lt - invalid  666 666  lt - invalid 1 111  1 111 11 1 111 110 01 111 110  lt - invalid 0 111 100  lt - invalid 11 11   lt - invalid 1 111  11  lt - invalid 1111 1 10  lt - invalid 01111 11 0  lt - invalid 0111 100   lt - invalid 1 111 111  1 111 111 11 1 111 111 110 01 111 111 110  lt - invalid 0 111 111 100  lt - invalid 1 111 111  1 1111 11 11  lt - invalid 11 111 11 110  lt - invalid 01 11 1111 110  lt - invalid 0 111111 100  lt - invalid 0002 22 2230  lt - invalid   5      lt - invalid 2 0 345 345  lt - invalid 2 334 456  lt - invalid

User · Answer

EDIT  Since this has gotten a lot of views  let me start by giving everybody what they Googled for    ALL THESE REQUIRE THE WHOLE STRING TO BE A NUMBER  For numbers embedded in sentences  see discussion below       NUMBERS AND DECIMALS ONLY       No commas allowed  Pass   1000 0    001     001   Fail   1 000 0    d     d     No commas allowed  Can t start with  quot   quot   Pass   0 01   Fail    01     d      d         CURRENCY       No commas allowed   quot   quot  optional  Can t start with  quot   quot   Either 0 or 2 decimal digits  Pass    1000    1 00     0 11   Fail    1 0    1      1 000      11       d     d 2           COMMA-GROUPED       Commas required between powers of 1 000  Can t start with  quot   quot   Pass   1 000 000    0 001   Fail   1000000    1 00 00 00     001    d 1 3    d 3       d       Commas required  Cannot be empty  Pass   1 000 100     001   Fail   1000              d 1 3    d 3         d       Commas optional as long as they re consistent  Can t start with  quot   quot   Pass   1 000 000    1000000   Fail   10000 000    1 00 00     d   d 1 3    d 3        d           LEADING AND TRAILING ZEROES       No commas allowed  Can t start with  quot   quot   No leading zeroes in integer part  Pass   1 00    0 00   Fail   001     1-9  d  0     d       No commas allowed  Can t start with  quot   quot   No trailing zeroes in decimal part  Pass   1    0 1   Fail   1 00    0 1000    d     d  1-9      Now that that s out of the way  most of the following is meant as commentary on how complex regex can get if you try to be clever with it  and why you should seek alternatives  Read at your own risk   This is a very common task  but all the answers I see here so far will accept inputs that don t match your number format  such as  111  9 9 9  or even       That s simple enough to fix  even if the numbers are embedded in other text  IMHO anything that fails to pull 1 234 56 and 1234   and only those numbers   out of abc22 1 234 56 9 9 9 9 def 1234 is a wrong answer  First of all  if you don t need to do this all in one regex  don t  A single regex for two different number formats is hard to maintain even when they aren t embedded in other text  What you should really do is split the whole thing on whitespace  then run two or three smaller regexes on the results  If that s not an option for you  keep reading  Basic pattern Considering the examples you ve given  here s a simple regex that allows pretty much any integer or decimal in 0000 format and blocks everything else     d     d    Here s one that requires 0 000 format     d 1 3    d 3       d      Put them together  and commas become optional as long as they re consistent      d     d   d 1 3    d 3       d       Embedded numbers The patterns above require the entire input to be a number  You re looking for numbers embedded in text  so you have to loosen that part  On the other hand  you don t want it to see catch22 and think it s found the number 22  If you re using something with lookbehind support  like  NET   this is pretty easy  replace   with    lt   S  and   with     S  and you re good to go      lt   S   d     d   d 1 3    d 3       d        S   If you re working with JavaScript or Ruby or something  things start looking more complex         s   d     d   d 1 3      d 3         d        S   You ll have to use capture groups  I can t think of an alternative without lookbehind support  The numbers you want will be in Group 1  assuming the whole match is Group 0   Validation and more complex rules I think that covers your question  so if that s all you need  stop reading now  If you want to get fancier  things turn very complex very quickly  Depending on your situation  you may want to block any or all of the following   Empty input Leading zeroes  e g  000123  Trailing zeroes  e g  1 2340000  Decimals starting with the decimal point  e g   001 as opposed to 0 001   Just for the hell of it  let s assume you want to block the first 3  but allow the last one  What should you do  I ll tell you what you should do  you should use a different regex for each rule and progressively narrow down your matches  But for the sake of the challenge  here s how you do it all in one giant pattern      lt   S       0   1-9   d   d 0 2    d 3           d  1-9       S   And here s what it means      lt   S  to     S   The whole match must be surrounded by either whitespace or line boundaries  So if you see something bogus like    9    ignore the 9                     The whole thing can t be blank                         Rules for the integer part    0                   1  The integer part could just be 0                              1-9                      otherwise  it can t have leading zeroes                              d                2  It could use no commas at all                                d 0 2    d 3           or it could be comma-separated groups of 3 digits each                                                3  Or there could be no integer part at all            Rules for the decimal part           1  It must start with a decimal point       d     2     followed by a string of numeric digits only     1-9   3  It can t be just the decimal point  and it can t end in 0           4  The whole decimal part is also optional  Remember  we checked at the beginning to make sure the whole thing wasn t blank   Tested here  http   rextester com YPG96786 This will allow things like  100 000 999 999 90 0009 1 000 023 999 0 111  111 0  It will block things like  1 1 1 111 000 001 111 999  0  111 110000 1 1 1 111 9 909 888  There are several ways to make this regex simpler and shorter  but understand that changing the pattern will loosen what it considers a number  Since many regex engines  e g  JavaScript and Ruby  don t support the negative lookbehind  the only way to do this correctly is with capture groups         s          0     1-9     d   d 0 2      d 3             d  1-9        S   The numbers you re looking for will be in capture group 1  Tested here  http   rubular com r 3HCSkndzhT One final note Obviously  this is a massive  complicated  nigh-unreadable regex  I enjoyed the challenge  but you should consider whether you really want to use this in a production environment  Instead of trying to do everything in one step  you could do it in two  a regex to catch anything that might be a number  then another one to weed out whatever isn t a number  Or you could do some basic processing  then use your language s built-in number parsing functions  Your choice

[regex] Regular expression to match numbers with or without commas and decimals in text

Examples related to regex