Test.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int is_closing_quote(char *template, int is_literal_string, int has_previous)
{
    if (!is_literal_string)
    {
	// is not \"
	return
	    (!has_previous || *(template - 1) != '\\') &&
	    (*template == '"');
    }
    // is not ''
    return
        (has_previous && *(template - 1) != '\'' && *template == '\'') ||
        (*template == '\'' && *(template + 1) != '\'') ;
}

int main(void) {
    // char* str = "ho-ya! \\\"\"";
    // printf("%d\n", is_closing_quote(str, 0, 0)); // 0
    // printf("%d\n", is_closing_quote(str + 8, 0, 1)); // 0
    // printf("%d\n", is_closing_quote(str + 9, 0, 1)); // 1

    char* lit = "ho-ya! '''";
    printf("%d\n", is_closing_quote(lit, 1, 0)); // 0
    printf("%d\n", is_closing_quote(lit + 7, 1, 0)); // 0
    printf("%d\n", is_closing_quote(lit + 8, 1, 0)); // 0
    printf("%d\n", is_closing_quote(lit + 9, 1, 0)); // 1
}