std::strcspn

 

C++

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Strings library

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Null-terminated byte strings

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isalnum isalpha islower isupper isdigit isxdigit isblank (C++11)	iscntrl isgraph isspace isprint ispunct tolower toupper
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String manipulation
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strlen strcmp strncmp strcoll strchr strrchr	strspn strcspn strpbrk strstr strtok
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Defined in header <cstring>
size_t strcspn( const char *dest, const char *src );

Returns the length of the maximum initial segment of the byte string pointed to by dest, that consists of only the characters not found in byte string pointed to by src.

The function name stands for "complementary span"

Parameters

dest	-	pointer to the null-terminated byte string to be analyzed
src	-	pointer to the null-terminated byte string that contains the characters to search for

Return value

The length of the maximum initial segment that contains only characters not found in the byte string pointed to by src

Example

Run this code

#include <string>
#include <cstring>
#include <iostream>
 
const char* invalid = "*$#";
int main()
{
    std::string s = "abcde312$#@";
 
    size_t valid_len = std::strcspn(s.c_str(), invalid);
    if(valid_len != s.size())
       std::cout << "'" << s << "' contains invalid chars starting aa position "
                 << valid_len << '\n';
}

Output:

'abcde312$#@' contains invalid chars starting aa position 8

See also

strspn	returns the length of the maximum initial segment that consists of only the characters found in another byte string (function)
wcscspn	returns the length of the maximum initial segment that consists of only the wide not found in another wide string (function)
strpbrk	finds the first location of any character from a set of separators (function)
C documentation for strcspn