How to find and replace string

Question

If s is a std  string  then is there a function like the following   s replace  text to replace    new text

User · Accepted Answer

Try a combination of std  string  find and std  string  replace   This gets the position   std  string s  std  string toReplace  text to replace    size t pos   s find toReplace     And this replaces the first occurrence   s replace pos  toReplace length     new text        Now you can simply create a function for your convenience   std  string replaceFirstOccurrence      std  string amp  s      const std  string amp  toReplace      const std  string amp  replaceWith        std  size t pos   s find toReplace       if  pos    std  string  npos  return s      return s replace pos  toReplace length    replaceWith

User · Answer

Yes  replace all is one of the boost string algorithms   Although it s not a standard library  it has a few things on the standard library    More natural notation based on ranges rather than iterator pairs  This is nice because you can nest string manipulations  e g   replace all nested inside a trim   That s a bit more involved for the standard library functions  Completeness  This isn t hard to be  better  at  the standard library is fairly spartan  For example  the boost string algorithms give you explicit control over how string manipulations are performed  i e   in place or through a copy

User · Answer

Do we really need a Boost library for seemingly such a simple task   To replace all occurences of a substring use this function   std  string ReplaceString std  string subject  const std  string amp  search                            const std  string amp  replace        size t pos   0      while   pos   subject find search  pos      std  string  npos             subject replace pos  search length    replace            pos    replace length              return subject      If you need performance  here is an optimized function that modifies the input string  it does not create a copy of the string   void ReplaceStringInPlace std  string amp  subject  const std  string amp  search                            const std  string amp  replace        size t pos   0      while   pos   subject find search  pos      std  string  npos             subject replace pos  search length    replace            pos    replace length              Tests   std  string input    abc abc def   std  cout  lt  lt   Input string     lt  lt  input  lt  lt  std  endl   std  cout  lt  lt   ReplaceString   return value                lt  lt  ReplaceString input   bc          lt  lt  std  endl  std  cout  lt  lt   ReplaceString   input string not modified                lt  lt  input  lt  lt  std  endl   ReplaceStringInPlace input   bc          std  cout  lt  lt   ReplaceStringInPlace   input string modified                lt  lt  input  lt  lt  std  endl    Output   Input string  abc abc def ReplaceString   return value  a   a   def ReplaceString   input string not modified  abc abc def ReplaceStringInPlace   input string modified  a   a   def

User · Answer

Not exactly that  but std  string has many replace  overloaded functions   Go through this link to see explanation of each  with examples as to how they re used   Also  there are several versions of string  find functions  listed below  which you can use in conjunction with string  replace    find    rfind   find first of find last of find first not of find last not of     Also  note that there are several versions of replace functions available from  lt algorithm gt  which you can also use  instead of string  replace     replace    replace if     replace copy   replace copy if

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like some say boost  replace all  here a dummy example        include  lt boost algorithm string replace hpp gt       std  string path  file gz        boost  replace all path    gz     zip

User · Answer

Here s the version I ended up writing that replaces all instances of the target string in a given string  Works on any string type     template  lt typename T  typename U gt  T  amp replace             T  amp str       const U  amp from       const U  amp to        size t pos      size t offset   0      const size t increment   to size         while   pos   str find from  offset      T  npos                str replace pos  from size    to           offset   pos   increment             return str      Example   auto foo    this is a test s  replace foo   is s   wis s   cout  lt  lt  foo    Output   thwis wis a test   Note that even if the search string appears in the replacement string  this works correctly

User · Answer

void replace char  str  char  strFnd  char  strRep        for  int i   0  i  lt  strlen str   i                  int npos   -1  j  k          if  str i     strFnd 0                         for  j   1  k   i 1  j  lt  strlen strFnd   j                    if  str k       strFnd j                       break              npos   i                    if  npos    -1              for  j   0  k   npos  j  lt  strlen strRep   j                    str k      strRep j             int main         char pst1      There is a wrong message       char pfnd      wrong       char prep      right        cout  lt  lt    nintial    lt  lt  pst1       replace pst1  pfnd  prep        cout  lt  lt    nfinal      lt  lt  pst1      return 0

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replaced text will be in buffer  void Replace char  buffer  const char  source  const char  oldStr   const char  newStr        if buffer  NULL    source    NULL    oldStr    NULL    newStr    NULL  return        int slen   strlen source       int olen   strlen oldStr       int nlen   strlen newStr        if olen gt slen  return      int ix 0       for int i 0 i lt slen i                  if oldStr 0     source i                         bool found   true              for int j 1 j lt olen j                                  if source i j   oldStr j                                         found   false                      break                                               if found                                for int j 0 j lt nlen j                        buffer ix      newStr j                    i   olen-1                             else                               buffer ix      source i                                   else                       buffer ix      source i

User · Answer

include  lt iostream gt   include  lt string gt  using namespace std   int main          string str  one three two four        string str2  three        str replace str find str2  str2 length    five        cout  lt  lt  str  lt  lt  endl      return 0      Output  one five two four

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void replaceAll std  string  amp  data  const std  string  amp toSearch  const std  string  amp replaceStr           Get the first occurrence     size t pos   data find toSearch          Repeat till end is reached     while  pos    std  string  npos                   Replace this occurrence of Sub String         data replace pos  toSearch size    replaceStr              Get the next occurrence from the current position         pos  data find toSearch  pos   replaceStr size               More CPP utilities  https   github com Heyshubham CPP-Utitlities blob master src MEString cpp L60

[c++] How to find and replace string?

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