string-related handler functions

1. strcpy:--Copy

Include library:

#include <string.h>

Function Prototypes:

Char *strcpy (char *dest, const char *SRC);

--Copy the string src points to the space pointed to by the dest, including the copy in SRC

Char *strncpy (char *dest, const char *SRC, size_t N);

--Copies the N-byte characters from SRC to the space pointed to by the dest, and does not intentionally add '% ' to the copy process

Parameters:

Dest, purpose

SRC, source

N, n bytes in the source

return value:

Pointer to the destination string dest

Example:

A simple implementation of the strcpy:

char * strncpy (char *dest, const char *SRC, size_t N)
{
size_t i;

for (i = 0; i < n && src[i]! = ' n '; i++)
Dest[i] = Src[i];
for (; i < n; i++)
Dest[i] = ' + ';

return dest;
}

For strncpy the current n characters do not have a string terminator, the solution is

strncpy (buf, str, n);

if (n > 0)

buf[n-1]= ' + ';

Note: The size of the target array must be large enough, otherwise there is a problem with the memory.

2. Strcat:--Connection

Included libraries:

#include <string.h>

Function Prototypes:

Char *strcat (char *dest, const char *SRC);

--Link src to dest behind, the result is dest+src. Connection method is

Start by overwriting the ' dest ' behind the string that the pointer is pointing to.

Char *strncat (char *dest, const char *SRC, size_t N);

--dest + A string of up to n src inside, special case is

When there are n or more n in the SRC, the SRC does not have to end with a '/'.

Parameters:

Dest, ...

Src...

Maximum number of n,src inside

return value:

Pointer to the destination string dest

Example:

A simple implementation of the STRNCAT:

char * STRNCAT (char *dest, const char *SRC, size_t N)
{
size_t Dest_len = strlen (dest);
size_t i;

for (i = 0; i < n && src[i]! = ' n '; i++)
Dest[dest_len + i] = src[i];
Dest[dest_len + i] = ' + ';

return dest;
}

3. strcmp: Compare

Included libraries:

#include <string.h>

Function Prototypes:

int strcmp (const char *S1, const char *S2);

--equivalent to *S1-*S2, all characters are compared

int strncmp (const char *S1, const char *S2, size_t N);

--equivalent to *S1-*S2, first n characters compared

Parameters:

S1, String 1

S2, String 2

N, (at most) the number to compare

return value:

The string that >0,s1 points to is larger than the string pointed to by S2

=0, two pointers to exactly the same string

The string that <0,s1 points to is smaller than the string pointed to by S2

Copyright NOTICE: This article for Bo Master original article, without Bo Master permission not reproduced.

string-related handler functions