How to check if a given substring within a string in C?
The code below compares whether they are equal, but if there is one inside the other.
#include <stdio.h>
#include <string.h>
int main( )
{
char str1[ ] = "test" ;
char str2[ ] = "subtest" ;
int i, j, k ;
i = strcmp ( str1, "test" ) ;
j = strcmp ( str1, str2 ) ;
k = strcmp ( str1, "t" ) ;
printf ( "\n%d %d %d", i, j, k ) ;
return 0;
}
surely, as @paddy pointed
inline bool issubstr(const char *string, const char *substring )
{
return( strstr(string, substring) ) ? true: false ;
}
ststr return a pointer to the beginning of the substring, or NULL if the substring is not found.
more on strstr and friends man page strstr
strstr returns a pointer to the first occurrence in str1 of the entire sequence of characters specified in str2, or a null pointer if the sequence is not present in str1.
you can use strstr
char str1[ ] = "subtest";
char str2[ ] = "test";
int index = -1;
char * found = strstr( str1, str2);
if (found != NULL)
{
index = found - str1;
}
You can use strstr() function as mentioned by paddy
strstr() function returns the first occurance of the substring in a string. If you are to find all occurances of a substring in a string than you have to use "String matching " algorithms such as,
1)Naive String Matching
2)Rabin Karp
3)Knuth Morris Pratt
Using strstr in <string.h>
char* str = "This is a test";
char* sub = "is";
char* pos = strstr(str, sub);
if (pos != NULL)
printf("Found the string '%s' in '%s'\n", sub, str);
Output:
Found the string 'is' in 'This is a test'
strstr