Linux C Programs (12)

String functions
C-language string-handling functions
1.puts function

1 // output A string ending with ' /' to the screen 2 Char " Welcome to " ; 3 Char " Linux C Program " ; 4 puts (a); 5 puts (p);

2.gets function

1 // Enter a character array from the terminal, returning the first address of the character array 2 Char string [+]; 3 gets (string); 4 puts (string); 5 // warning:the ' gets ' function is dangerous and should isn't be used. 6 // the system is not recommended to use the Gets method, dangerous

3.strcpy and strncpy

1 #include <string.h>2char *strcpy (charChar *src); 3 Char *strncpy (charchar *src,int n); // The first n characters of the copy 4 // strcpy is a string copy abbreviation, and using both functions must contain string.h, and the return value is Dest 5 // Copied together with ' + '

Replication error Code Demonstration:

1 Char "  " , b[); 2 b = A; 3 // string copying can only use functions such as strcpy

strcpy unsafe, easy to be exploited by hackers, generally with strncpy
Example code:

1 Char " Hello WORLG " ; 2 Char d1[(],d2[); 3 strcpy (d1,s); 4 strncpy (d2,s,sizeof(s)); 5 // 6 // strncpy Copy Incomplete ... 

4.strcat and Strncat

1 #include <string.h>2char *strcat (charChar *src); 3 Char *strncat (charchar *src,int n); // The first n characters of the copy 4 // append the input src to the tail of the dest 5 // strcat Not Safe

5.STRCMP and STRNCMP

1 #include <string.h>2char *strcmp (charchar *s2); // comparison of two strings 3 Char *strncmp (charchar *s2,int n); // Compare top N strings 4 // when different characters are first encountered, the difference of S1-S2 is the return value

6.strlen

1 #include <string.h> 2 // returns the actual length of the string, does not include the Terminator '% ', sizeof (s) The calculation will contain a Terminator

Abbreviations for 7.STRLWR and strupr//string lower and string upper

8.strstr and STRCHR

1#include <string.h>2 Char*STRSTR (Char*S1,Char*S2);//looking for S2 in S1, returning the first pointer to the S2 position, no return null found3 Char*STRCHR (Char*S1,Charc);//S1 looks for the position where C first appears, returns a pointer, and does not return null4 //----5#include <stdio.h>6#include <string.h>7 8 intMain () {9         Char*S1 ="liunx C Program", *s2="Unx",*p;Ten  Onep =strstr (S1,S2); A         if(P! =NULL) { -printf"%s\n", p); -}Else{ theprintf"Not found!"); -         } -  -P= STRCHR (S1,'C'); +         if(P! =NULL) { -printf"%s\n", p); +}Else{ Aprintf"Not found!"); at         } -         return 0; -}

Linux C Programs (12)