What will be the output of the following C code?
const char str1[]="ABCDEF1234567";
const char str2[] = "269";
len = strcspn(str1, str2);
printf("First matching character is at %d\n", len + 1);
Answer: A
size_t strcspn(const char *str1, const char *str2) is used to calculate the length of the initial segment of str1, which consists entirely of characters not in str2.