YouTipC Function Strspn
# C Library Function - strspn()
[ C Standard Library - ](#)
## Description
The C library function **size_t strspn(const char *str1, const char *str2)** retrieves the index of the first character in string **str1** that is not present in string **str2**.
## Declaration
Below is the declaration for the strspn() function.
size_t strspn(const char *str1, const char *str2)
## Parameters
* **str1** -- The C string to be scanned.
* **str2** -- The string containing the list of characters to match in str1.
## Return Value
This function returns the index of the first character in str1 that is not present in string str2.
## Example
The following example demonstrates the usage of the strspn() function.
## Example
#include
#include
int main ()
{
int len;
const char str1[]="ABCDEFG019874";
const char str2[]="ABCD";
len =strspn(str1, str2);
printf("Initial segment matching length %dn", len );
return(0);
}
Let us compile and run the above program, which will produce the following result:
Initial segment matching length 4
[ C Standard Library - ](#)