Convert char array to single int

Question

Anyone know how to convert a char array to a single int    char hello 5   hello    12345    int myNumber   convert char to int hello   Printf  My number is   d   myNumber

User · Answer

I use    int convertToInt char a 1000        int i   0      int num   0      while  a i     0                num     a i  -  0       num   10           i              return num

User · Answer

There are mulitple ways of converting a string to an int   Solution 1   Using Legacy C functionality  int main           char hello 5              hello    12345     --- gt This wont compile      char hello      12345        Printf  My number is   d   atoi hello          return 0      Solution 2  Using lexical cast Most Appropriate  amp  simplest   int x   boost  lexical cast lt int gt   12345       Solution 3  Using C   Streams  std  string hello  123     std  stringstream str hello    int x    str  gt  gt  x    if   str                 The conversion failed

User · Answer

If you are using C  11  you should probably use stoi because it can distinguish between an error and parsing  0    try       int number   std  stoi  1234abc      catch  std  exception const  amp e           This could not be parsed into a number so an exception is thrown         atoi   would return 0  which is less helpful if it could be a valid value      It should be noted that  1234abc  is implicitly converted from a char   to a std string before being passed to stoi

User · Answer

Long story short you have to use atoi    ed    If you are interested in doing this the right way     char szNos      12345   char  pNext  long output  output   strtol  szNos   amp pNext  10      input  ptr to next char in szNos  null here   base

User · Answer

Use sscanf     sscanf example     include  lt stdio h gt   int main        char sentence     Rudolph is 12 years old     char str  20     int i     sscanf  sentence   s   s  d  str  amp i     printf    s - gt   d n  str i      return 0

User · Answer

I ll just leave this here for people interested in an implementation with no dependencies   inline int stringLength  char  String            int Count   0      while   String        Count      return Count         inline int stringToInt  char  String            int Integer   0      int Length   stringLength String       for  int Caret   Length - 1  Digit   1  Caret  gt   0  -- Caret  Digit    10                    if  String Caret      -   return Integer   -1          Integer     String Caret  -  0     Digit                 return Integer          Works with negative values  but can t handle non-numeric characters mixed in between  should be easy to add though   Integers only

User · Answer

Ascii string to integer conversion is done by the atoi   function

[c++] Convert char array to single int?

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