I’ve been privileged by higher-level language string functions, such as PHP’s easy to use str_replace function, that I’ve forgotten how performing such simple tasks in lower-level languages like C++ can be such a hassle. Aside from using some library (of which I’m not aware yet), here’s a simple string replace function which is similar to the PHP version. In this case the function will directly modify the original string, not return an instance of a new string.

void str_replace(std::string& str, const std::string find, const std::string replace){
	size_t index = 0;
	while (true) {
		 /* Locate the substring to replace. */
		 index = str.find(find, index);
		 if (index == std::string::npos) break;

		 /* Make the replacement. */
		 str.replace(index, find.length(), replace);

		 /* Advance index forward one spot so the next iteration doesn't pick it up as well. */
		 ++index;
	}
}

Usage:

std::string str = "Hello Earth!";
str_replace(str,"Earth","World");
//str is "Hello World!" now.