std::strncmp

 

C++

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Strings library

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Null-terminated byte strings

Functions
Character manipulation
isalnum isalpha islower isupper isdigit isxdigit isblank (C++11)	iscntrl isgraph isspace isprint ispunct tolower toupper
Conversions to numeric formats
atof atoiatolatoll strtolstrtoll	strtoulstrtoull strtofstrtodstrtold
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strlen strcmp strncmp strcoll strchr strrchr	strspn strcspn strpbrk strstr strtok
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memcmp
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Defined in header <cstring>
int strncmp( const char* lhs, const char* rhs, size_t count );

Compares at most count characters of two null-terminated byte strings. The comparison is done lexicographically.

Parameters

lhs, rhs	-	pointers to the null-terminated byte strings to compare
count	-	maximum number of characters to compare

Return value

Negative value if lhs is less than rhs.

​0​ if lhs is equal to rhs.

Positive value if lhs is greater than rhs.

Example

Run this code

#include <iostream>
#include <cstring>
 
int main() 
{
    const char world[] = "Hello, world!";
    const char everybody[] = "Hello, everybody!";
    const char somebody[] = "Hello, somebody!";
 
    // Compares 13 characters of "Hello, world!" and "Hello, everybody!"
    std::cout << std::strncmp(world, everybody, sizeof(world) - 1) << '\n';
 
    // Compares 13 characters of "Hello, everybody!" and "Hello, world!"
    std::cout << std::strncmp(everybody, world, sizeof(world) - 1) << '\n';
 
    // Compares 7 characters of "Hello, everybody!" and "Hello, world!"
    std::cout << std::strncmp(everybody, world, sizeof("Hello, ") - 1) << '\n';
 
    // Compares 5 characters of "Hello, everybody!" and "Hello, somebody!"
    //                                       ^                      ^
    std::cout << std::strncmp(&everybody[12], &somebody[11], sizeof("body!") - 1) << '\n';
}

Output:

1
-1
0
0

See also

strcmp	compares two strings (function)
memcmp	compares two buffers (function)
strcoll	compares two strings in accordance to the current locale (function)
C documentation for strncmp