C++ substr functionThe STL provides us with substr function, but it is lacking. For one it requires 2 parameters, instead of defaulting on the second. The php substr function also provides the ability to use negative 'start' position and negative lengths.
#include <iostream> #include <string> using namespace std; string substr(const string &str, int start); string substr(const string &str, int start, int length); int main(int argc, char *argv[]) { cout << substr("abcdef", -1) << endl; // "f" cout << substr("abcdef", -2) << endl; // "ef" cout << substr("abcdef", -3, 1) << endl; // "d" cout << substr("abcdef", 0, -1) << endl; // "abcde" cout << substr("abcdef", 2, -1) << endl; // "cde" cout << substr("abcdef", 4, -4) << endl; // "" cout << substr("abcdef", -3, -1) << endl; // "de" cout << substr("abcdef", 1) << endl; // "bcdef" cout << substr("abcdef", 1, 3) << endl; // "bcd" cout << substr("abcdef", 0, 4) << endl; // "abcd" cout << substr("abcdef", 0, 8) << endl; // "abcdef" cout << substr("abcdef", -1, 1) << endl; // "f" } string substr(const string &str, int start) { return substr(str,start,str.length()); } string substr(const string &str, int start, int length) { if (start < 0 ) start+=str.length(); if (length < 0 ) length=str.length()+length-start; if (length < 0 ) return ""; return str.substr(start,length); } I used test cases from the php website. Having 2 functions the same name with slightly different parameters is an example of function overloading. This function allows for negative starts and negative lengths, to mimic the php string function. Tags: c++ | Related Articles |
©2010, Zedwood Digital