#include #include // Find the first instance of c in str // Returns -1 if c is not found int strindexof(char c, const char *str) { for (size_t i = 0; i < strlen(str); i++) { if (str[i] == c) return i; } return -1; } // Find the length of a string size_t strlen(const char *str) { size_t len = 0; while (str[len] != 0) len++; return len; }