Checking for Prefix String Existence and Converting a Substring to Integer in C

A user seeks guidance on implementing Python's string prefix checking and substring conversion in C . Specifically, they aim to achieve the functionality of Python's startswith() method and substring conversion to an integer.

Checking Prefix String Existence

To check if a C string starts with a specific prefix, leverage the rfind() method with a search position of zero. For example:

std::string s = "tititoto";
if (s.rfind("titi", 0) == 0) {
  // s starts with "titi"
}

By setting the search position to zero, the rfind() method only checks the beginning of the string. This allows for efficient and accurate prefix matching.

Converting a Substring to an Integer

To convert a substring to an integer, use the stoi() function:

if (s.rfind("--foo=", 0) == 0) {
    int foo_value = std::stoi(s.substr(strlen("--foo=")));
}

This code checks for the "--foo=" prefix and, if found, extracts the substring starting from its end (after the "=" character) and converts it to an integer using stoi().

Update: Boost Integration

The user expresses reluctance to employ Boost. However, they are free to use it if desired. Boost provides additional string manipulation capabilities, including starts_with() and stoi() functionality in its Spirit Library.