strncmp
From cppreference.com
Defined in header <string.h>
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int strncmp( const char *lhs, const char *rhs, size_t count ); |
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Compares at most count
characters of two possibly null-terminated arrays. The comparison is done lexicographically.
The sign of the result is the sign of the difference between the values of the first pair of characters (both interpreted as unsigned char) that differ in the arrays being compared.
The behavior is undefined when access occurs past the end of either array lhs
or rhs
. The behavior is undefined when either lhs
or rhs
is the null pointer.
Parameters
lhs, rhs | - | pointers to the possibly null-terminated arrays to compare |
count | - | maximum number of characters to compare |
Return value
Negative value if lhs
appears before rhs
in lexicographical order.
Zero if lhs
and rhs
compare equal, or if count is zero.
Positive value if lhs
appears after rhs
in lexicographical order.
Notes
This function is not locale-sensitive, unlike strcoll and strxfrm.
Example
Run this code
#include <string.h> #include <stdio.h> void demo(const char* lhs, const char* rhs, int sz) { int rc = strncmp(lhs, rhs, sz); if(rc == 0) printf("First %d chars of [%s] equal [%s]\n", sz, lhs, rhs); else if(rc < 0) printf("First %d chars of [%s] precede [%s]\n", sz, lhs, rhs); else if(rc > 0) printf("First %d chars of [%s] follow [%s]\n", sz, lhs, rhs); } int main(void) { const char* string = "Hello World!"; demo(string, "Hello!", 5); demo(string, "Hello", 10); demo(string, "Hello there", 10); demo("Hello, everybody!" + 12, "Hello, somebody!" + 11, 5); }
Output:
First 5 chars of [Hello World!] equal [Hello!] First 10 chars of [Hello World!] follow [Hello] First 10 chars of [Hello World!] precede [Hello there] First 5 chars of [body!] equal [body!]
References
- C11 standard (ISO/IEC 9899:2011):
- 7.24.4.4 The strncmp function (p: 366)
- C99 standard (ISO/IEC 9899:1999):
- 7.21.4.4 The strncmp function (p: 329)
- C89/C90 standard (ISO/IEC 9899:1990):
- 4.11.4.4 The strncmp function
See also
compares two strings (function) | |
(C95) |
compares a certain amount of characters from two wide strings (function) |
compares two buffers (function) | |
compares two strings in accordance to the current locale (function) |