C++ strcspn() is an inbuilt function that is used for string handling. It is defined in string.h header file. The strcspn() function calculates a length of the characters before the first occurrence of that particular character in both the strings. In simpler words, it searches for the characters of one string in another string.
C++ strcspn() Function
The strcspn() function in C++ takes two null-terminated byte string: dest and src as its argument and searches dest for any characters that are present in src.
Syntax
size_t strcspn(const char *str_var1, const char *str_var2);
Here str_var1 and str_var2 are the string variables that will be used for all the operations using this function.
Parameters
The C++ strcspn() function takes two parameters str_var1 and str_var2. Here the function searches for the str_var1 for any characters that are present in str_var2.
Return Value
The strcspn() function returns a number of characters before the occurrence of a particular specified character in both the strings.
Example programs on strcspn() in C++
Example 1: Write a program to show the working of strcspn() in C++
#include <iostream>
#include <string.h>
using namespace std;
int main()
{
char k[] = "qwerty";
char f[] = "rt";
int len;
len = strcspn(k, f);
cout << "Length of character before occurance of the second string: " << len;
return 0;
}Output
Length of character before the occurrence of the second string: 3
Example 2: Write a program to pass character to be scanned, which not present and hence show the output.
#include <iostream>
#include <string.h>
using namespace std;
int main()
{
char k[] = "Messi";
char f[] = "ro";
int len;
len = strcspn(k, f);
cout << len;
cout << "Sorry nothing matches in the above string, so the unmatched length: " << len << endl;
return 0;
}Output
Sorry nothing matches in the above string, so the unmatched length: 5
Returns a length of the maximum initial segment of the byte string pointed to by k, which consists of only the characters not found in a byte string pointed to by f.
In the above code, the char f = “ro” is not included in “Messi“, so it will return. Sorry, nothing matches in the above string, so the unmatched length.
Conclusion
The C++ strcspn(const char *str1, const char *str2) calculates a length of the initial segment of str1, which consists wholly of characters, not in str2.
