How to get file extension from string in C++

Question

Given a string \"filename.conf\", how to I verify the extension part?

I need a cross platform solution.

Answer 1

You can use strrchr() to find last occurence of .(dot) and get .(dot) based extensions files. Check the below code for example.

#include<stdio.h>

void GetFileExtension(const char* file_name) {

    int ext = '.';
    const char* extension = NULL;
    extension = strrchr(file_name, ext);

    if(extension == NULL){
        printf("Invalid extension encountered\n");
        return;
    }

    printf("File extension is %s\n", extension);
}

int main()
{
    const char* file_name = "c:\\.directoryname\\file.name.with.too.many.dots.ext";
    GetFileExtension(file_name);
    return 0;
}