Find dangerous C functions in toy source

Challenge

Write a tiny static-analysis pass that counts calls to high-risk C functions in a snippet of source text.

Task

Implement int count_dangerous_calls(const char *source) that counts how many times any of these names appears as a function call in source: strcpy, strcat, sprintf, gets, system.

A call is the exact identifier immediately followed by (, with optional whitespace between the name and the (. The match must be on a whole identifier — mystrcpy( and strcpyx( do not count.

Input

• source: a NUL-terminated string of C source text. The grader passes a fixed snippet baked into the harness.

Output

Returns a non-negative int: the total number of matching calls (each occurrence counts once).

Example

"strcpy(a, b);"                              ->   1
"mystrcpy(a, b);"                            ->   0   (substring, not a call)
"gets(buf); sprintf(out, \"hi\"); strcat(a, b);"  ->   3
"strcpy   (a,b);"                            ->   1   (whitespace before `(`)

Edge cases

• No dangerous calls returns 0.
• Whitespace (spaces/tabs) is allowed between the name and (.
• The previous character must not be a letter, digit, or _ (otherwise it is part of a longer identifier).

Rules

• Operate only on the string the grader passes — no file or network I/O.

Input format

A NUL-terminated string source of C source text.

Output format

A non-negative int: the count of dangerous-function calls found.

Constraints

Match whole identifiers followed by ( (whitespace allowed); operate on the buffer only.

Starter code

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

int count_dangerous_calls(const char *source) {
    /* TODO */
    return 0;
}