Find out if string ends with another string in C

Question

How can I find out if a string ends with another string in C

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you can use string  rfind  The full Example based on comments   bool EndsWith string  amp str  string amp  key    size t keylen   key length    size t strlen   str length     if keylen   lt  strlen      return string  npos    str rfind key strlen - keylen  keylen   else return false

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Regarding Grzegorz Bazior response  I used this implementation  but original one has bug  returns true if I compare      with   so    I propose modified function   bool endsWith const string amp  s  const string amp  suffix        return s size    gt   suffix size    amp  amp  s rfind suffix      s size  -suffix size

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Use boost  algorithm  ends with  see e g  http   www boost org doc libs 1 34 0 doc html boost algorithm ends with html      include  lt boost algorithm string predicate hpp gt      works with const char   assert boost  algorithm  ends with  mystring    ing         also works with std  string std  string haystack  mystring    std  string needle  ing    assert boost  algorithm  ends with haystack  needle     std  string haystack2  ng    assert   boost  algorithm  ends with haystack2  needle

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Let a be a string and b the string you look for  Use a substr to get the last n characters of a and compare them to b  where n is the length of b   Or use std  equal  include  lt algorithm gt    Ex   bool EndsWith const string amp  a  const string amp  b        if  b size    gt  a size    return false      return std  equal a begin     a size   - b size    a end    b begin

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My two cents   bool endsWith std  string str  std  string suffix       return str find suffix  str size   - suffix size       string  npos

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bool EndsWith const std  string amp  data  const std  string amp  suffix        return data find suffix  data size   - suffix size       string  npos      Tests  include  lt iostream gt  int main        cout  lt  lt  EndsWith u8 quot o hello 1 quot   u8 quot o  quot    lt  lt  endl      cout  lt  lt  EndsWith u8 quot o hello  quot   u8 quot o  quot    lt  lt  endl      cout  lt  lt  EndsWith u8 quot hello  quot   u8 quot o  quot    lt  lt  endl      cout  lt  lt  EndsWith u8 quot o hello o  quot   u8 quot o  quot    lt  lt  endl      return 0     Output 0  1  1  1

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I thought it makes sense to post a raw solution that doesn t use any library functions        Checks whether  str  ends with  suffix  bool endsWith const std  string amp  str  const std  string amp  suffix        if   amp suffix     amp str  return true     str and suffix are the same string     if  suffix length    gt  str length    return false      size t delta   str length   - suffix length        for  size t i   0  i  lt  suffix length      i            if  suffix i     str delta   i   return false            return true      Adding a simple std  tolower we can make this case insensitive     Checks whether  str  ends with  suffix  ignoring case bool endsWithIgnoreCase const std  string amp  str  const std  string amp  suffix        if   amp suffix     amp str  return true     str and suffix are the same string     if  suffix length    gt  str length    return false      size t delta   str length   - suffix length        for  size t i   0  i  lt  suffix length      i            if  std  tolower suffix i      std  tolower str delta   i    return false            return true

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Note  that starting from c  20 std  string will finally provide starts with and ends with  Seems like there is a chance that by c  30 strings in c   might finally become usable  if you aren t reading this from distant future  you can use these startsWith endsWith with C  17   if   cplusplus  gt   201703L    C  17 and later   include  lt string view gt   static bool endsWith std  string view str  std  string view suffix        return str size    gt   suffix size    amp  amp  0    str compare str size  -suffix size    suffix size    suffix      static bool startsWith std  string view str  std  string view prefix        return str size    gt   prefix size    amp  amp  0    str compare 0  prefix size    prefix      endif    C  17  If you are stuck with older C    you may use these   if   cplusplus  lt  201703L    pre C  17  include  lt string gt   static bool endsWith const std  string amp  str  const std  string amp  suffix        return str size    gt   suffix size    amp  amp  0    str compare str size  -suffix size    suffix size    suffix      static bool startsWith const std  string amp  str  const std  string amp  prefix        return str size    gt   prefix size    amp  amp  0    str compare 0  prefix size    prefix      and some extra helper overloads  static bool endsWith const std  string amp  str  const char  suffix  unsigned suffixLen        return str size    gt   suffixLen  amp  amp  0    str compare str size  -suffixLen  suffixLen  suffix  suffixLen      static bool endsWith const std  string amp  str  const char  suffix        return endsWith str  suffix  std  string  traits type  length suffix       static bool startsWith const std  string amp  str  const char  prefix  unsigned prefixLen        return str size    gt   prefixLen  amp  amp  0    str compare 0  prefixLen  prefix  prefixLen      static bool startsWith const std  string amp  str  const char  prefix        return startsWith str  prefix  std  string  traits type  length prefix       endif  IMO  c   strings are clearly dysfunctional  and weren t made to be used in real world code  But there is a hope that this will get better at least

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Simply compare the last n characters using std  string  compare    include  lt iostream gt   bool hasEnding  std  string const  amp fullString  std  string const  amp ending        if  fullString length    gt   ending length              return  0    fullString compare  fullString length   - ending length    ending length    ending          else           return false           int main          std  string test1    binary       std  string test2    unary       std  string test3    tertiary       std  string test4    ry       std  string ending    nary        std  cout  lt  lt  hasEnding  test1  ending   lt  lt  std  endl      std  cout  lt  lt  hasEnding  test2  ending   lt  lt  std  endl      std  cout  lt  lt  hasEnding  test3  ending   lt  lt  std  endl      std  cout  lt  lt  hasEnding  test4  ending   lt  lt  std  endl       return 0

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The std  mismatch method can serve this purpose when used to backwards iterate from the end of both strings   const string sNoFruit    ThisOneEndsOnNothingMuchFruitLike   const string sOrange    ThisOneEndsOnOrange    const string sPattern    Orange    assert  mismatch  sPattern rbegin    sPattern rend    sNoFruit rbegin                first    sPattern rend       assert  mismatch  sPattern rbegin    sPattern rend    sOrange rbegin                first    sPattern rend

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bool endswith const std  string  amp str  const std  string  amp suffix        string  size type totalSize   str size        string  size type suffixSize   suffix size         if totalSize  lt  suffixSize            return false             return str compare totalSize - suffixSize  suffixSize  suffix     0

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Use std  equal algorithm from  lt algorithms gt  with reverse iteration   std  string LogExt     log   if  std  equal LogExt rbegin    LogExt rend    filename rbegin

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Let me extend Joseph s solution with the case insensitive version  online demo   include  lt string gt   include  lt cctype gt   static bool EndsWithCaseInsensitive const std  string amp  value  const std  string amp  ending        if  ending size    gt  value size              return false            return std  equal ending crbegin    ending crend    value crbegin               const unsigned char a  const unsigned char b                return std  tolower a     std  tolower b

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Use this function   inline bool ends with std  string const  amp  value  std  string const  amp  ending        if  ending size    gt  value size    return false      return std  equal ending rbegin    ending rend    value rbegin

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the very same as above  here is my solution   template lt typename TString gt    inline bool starts with const TString amp  str  const TString amp  start        if  start size    gt  str size    return false      return str compare 0  start size    start     0        template lt typename TString gt    inline bool ends with const TString amp  str  const TString amp  end        if  end size    gt  str size    return false      return std  equal end rbegin    end rend    str rbegin

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another option is to use regex  The following code makes the search insensitive to upper lower case   bool endsWithIgnoreCase const std  string amp  str  const std  string amp  suffix      return std  regex search str       std  regex std  string suffix         std  regex constants  icase        probably not so efficient  but easy to implement

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If you re like me and no so into C   purism  here s an old skool hybrid  There s some advantage when strings are more than a handful of characters  as most memcmp implementations compare machine words when possible   You need to be in control of the character set  For example  if this approach is used with utf-8 or wchar type  there s some disadvantage as it won t support character mapping - e g   when two or more characters are logically identical   bool starts with std  string const  amp  value  std  string const  amp  prefix        size t valueSize   value size        size t prefixSize   prefix size         if  prefixSize  gt  valueSize                return false             return memcmp value data    prefix data    prefixSize     0      bool ends with std  string const  amp  value  std  string const  amp  suffix        size t valueSize   value size        size t suffixSize   suffix size         if  suffixSize  gt  valueSize                return false             const char   valuePtr   value data     valueSize - suffixSize       return memcmp valuePtr  suffix data    suffixSize     0

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I know the question s for C    but if anyone needs a good ol  fashioned C function to do this         returns 1 iff str ends with suffix     int str ends with const char   str  const char   suffix       if  str    NULL    suffix    NULL       return 0     size t str len   strlen str     size t suffix len   strlen suffix      if suffix len   str len      return 0     return 0    strncmp  str   str len - suffix len  suffix  suffix len

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Found this nice answer to the similar  startWith -problem   How do I check if a C   std  string starts with a certain string  and convert a substring to an int   You can adopt the solution to only search at the last place in the string   bool endsWith const std  string amp  stack  const std  string amp  needle        return stack find needle  stack size   - needle size       std  string  npos      This way you can make it short  fast  use standard c   and make it readable

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In my opinion simplest  C   solution is  bool endsWith const string amp  s  const string amp  suffix        return s rfind suffix     std  abs s size  -suffix size        Warning  If the match fails  this will search the entire string backwards before giving up  and thus potentially waste a lot of cycles

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Check if str has suffix  using below      Check string is end with extension suffix    int strEndWith char  str  const char  suffix      size t strLen   strlen str     size t suffixLen   strlen suffix     if  suffixLen  lt   strLen        return strncmp str   strLen - suffixLen  suffix  suffixLen     0        return 0

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