I have two char arrays char search_array[8] and input_array[30] and I'm getting the characters by using getchar, but I want to find if the search array exists in input array without using string library.
Example:
search array: hello
input array hello, how are you
You need some string comparison loop, like that of which you can find in strcmp or strcspn. This is assuming you use a terminal value like C strings; if you use some length field you'll need to make adjustments to the loops to account for those clearly. Here are some examples:
int strcmp(char const *x, char const *y) {
while (*x && *x == *y) {
x++;
y++;
}
return ((unsigned)*x > (unsigned)*y) - ((unsigned)*x < (unsigned)*y);
}
size_t strcspn(char const *x, char const *y) {
char const *x_ = x;
while (*x_) {
for (char const *y_ = y; *y_; y_++) {
if (*x_ == *y_)
return x_ - x;
}
x_++;
}
return x_ - x;
}
strcmp implementation: the characters should be converted to unsigned char for comparison in the return statement. In strcspn, you should duplicate the return statement instead of using goto.
(unsigned)*x > (unsigned)*y). It is the same result as (unsigned char)*x > (unsigned char)*y).int/unsigned than char types. Of course this is all micro-optimizations.return (unsigned char)*x - (unsigned char)*y; is even better on architectures where UCHAR_MAX < INT_MAX.The obvious solution for your goal is to use the standard library's strstr function.
Since you are not allowed to use the string library, you should write your own version of strstr and use that.
Here is a simple yet conforming implementation:
char *my_strstr(const char *s1, const char *s2) {
for (;;) {
for (size_t i = 0;; i++) {
if (s2[i] == '\0')
return (char *)s1;
if (s1[i] != s2[i])
break;
}
if (*s1++ == '\0')
return NULL;
}
}
You then use this function this way:
if (my_strstr(input_array, search_array)) {
printf("string was found\n");
} else {
printf("string was not found\n");
}
strstr and use it with search_array and input_array. If you are not allowed to write functions, you could duplicate the above code, initializing s1 to point to input_array and s2 to point to search_array...