std::strncmp

 

C++

Language

Standard library headers

Concepts

Utilities library

Strings library

Containers library

Algorithms library

Iterators library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

 

Strings library

Null-terminated strings

Byte strings

Multibyte strings

Wide strings

Classes

basic_string

char_traits

 

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 atoi atol atoll strtol strtoll	strtoul strtoull strtof strtod strtold
String manipulation
strcpy
strncpy
strcat
strncat
strxfrm
String examination
strlen strcmp strncmp strcoll strchr strrchr	strspn strcspn strpbrk strstr strtok
Memory manipulation
memchr
memcmp
memset
memcpy
memmove
Miscellaneous
strerror

 

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 8 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)