How to replace all occurrences of a character in string?

Question

What is the effective way to replace all occurrences of a character with another character in std::string?

Answer 1

The question is centered on character replacement, but, as I found this page very useful (especially Konrad's remark), I'd like to share this more generalized implementation, which allows to deal with substrings as well:

std::string ReplaceAll(std::string str, const std::string& from, const std::string& to) {
    size_t start_pos = 0;
    while((start_pos = str.find(from, start_pos)) != std::string::npos) {
        str.replace(start_pos, from.length(), to);
        start_pos += to.length(); // Handles case where 'to' is a substring of 'from'
    }
    return str;
}

Usage:

std::cout << ReplaceAll(string("Number Of Beans"), std::string(" "), std::string("_")) << std::endl;
std::cout << ReplaceAll(string("ghghjghugtghty"), std::string("gh"), std::string("X")) << std::endl;
std::cout << ReplaceAll(string("ghghjghugtghty"), std::string("gh"), std::string("h")) << std::endl;

Outputs:

Number_Of_Beans

XXjXugtXty

hhjhugthty

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EDIT:

The above can be implemented in a more suitable way, in case performances are of your concern, by returning nothing (void) and performing the changes directly on the string str given as argument, passed by address instead of by value. This would avoid useless and costly copy of the original string, while returning the result. Your call, then...

Code :

static inline void ReplaceAll2(std::string &str, const std::string& from, const std::string& to)
{
    // Same inner code...
    // No return statement
}

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Hope this will be helpful for some others...