It all depends on how the file is formatted and how deeply you want to scan. If the int is a word of its own and not part of a larger word, you can just read words and check for the int:
bool is_int(char const* s, int* value)
// Fill in this function. strtol() is a good start for testing for int.
FILE* fp = fopen("file", "r");
int needle = /* The int being searched */;
while (fscanf(fp, "%s", word) == 1)
if (is_int(word, &value) && value == needle)