Count character occurrences in a string in C++

Question

#include <algorithm>

std::string s = "a_b_c";
size_t n = std::count(s.begin(), s.end(), '_');

Pseudocode:

count = 0
For each character c in string s
  Check if c equals '_'
    If yes, increase count

EDIT: C++ example code:

int count_underscores(string s) {
  int count = 0;

  for (int i = 0; i < s.size(); i++)
    if (s[i] == '_') count++;

  return count;
}

Note that this is code to use together with std::string, if you're using char*, replace s.size() with strlen(s).

Also note: I can understand you want something "as small as possible", but I'd suggest you to use this solution instead. As you see you can use a function to encapsulate the code for you so you won't have to write out the for loop everytime, but can just use count_underscores("my_string_") in the rest of your code. Using advanced C++ algorithms is certainly possible here, but I think it's overkill.

Old-fashioned solution with appropriately named variables. This gives the code some spirit.

#include <cstdio>
int _(char*__){int ___=0;while(*__)___='_'==*__++?___+1:___;return ___;}int main(){char*__="_la_blba_bla__bla___";printf("The string \"%s\" contains %d _ characters\n",__,_(__));}

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Edit: about 8 years later, looking at this answer I'm ashamed I did this (even though I justified it to myself as a snarky poke at a low-effort question). This is toxic and not OK. I'm not removing the post; I'm adding this apology to help shifting the atmosphere on StackOverflow. So OP: I apologize and I hope you got your homework right despite my trolling and that answers like mine did not discourage you from participating on the site.

#include <boost/range/algorithm/count.hpp>

std::string str = "a_b_c";
int cnt = boost::count(str, '_');