do not try to modified the value in const region

2495 단어 functionStringubuntu
I run into this troublesome in the morning , I realize how foolish I did suddenly , as you the title says, "do not try to modified the value in const region".
I write a funciton to reverse a string , fortunately I give a string array to it's argment firstly, it ok,
however it's show "segmentation fault", when I try to give string to it by a point:
 
/* strrev.c by vinco at 2011-08-04
   Ubuntu9.10 CC/GCC
*/
#include<stdio.h>
#include<string.h>
#include<stdlib.h>

char* strrev(char* str);

int main()
{
#if 0
	char* str = "vinco zhang";
	//char* p ="vinco zhang";
	//char* str = (char*) malloc(32);
	//strcpy(str,p);
#else
	char str[]="vinco zhang";
#endif
	//strrev(str);
	//printf("strrev : str = %s
",str); printf("strrev : str = %s
", strrev(str) ); return 0; } char* strrev(char* str) { char* p = str; char t; int i=0, len = strlen(str) - 1; for(i=0 ; i<len ; i++, len--) { t = *(p+i) ; *(p+i) = *(p+len) ; *(p+len) = t ; } return str; }

1. case #if 0, I give a string array to strrev(), it work well:
root@vinco:/home/vinco# make strrev
cc     strrev.c   -o strrev
root@vinco:/home/vinco# ./strrev
strrev : str = gnahz ocniv
root@vinco:/home/vinco# 

2. case #if 1,"segmentation fault"
root@vinco:/home/vinco# make strrev
cc     strrev.c   -o strrev
root@vinco:/home/vinco# ./strrev 
Segmentation fault

3, to void the problem, as you see:
   i. do as case #if 0
   ii. so as the comment :( it's just a liite troublesome , but it done)
        char* p ="vinco zhang";
        char* str = (char*) malloc(32);
        strcpy(str,p);

Summary:
1.do not try to modified the value in const region ;
2.the funciton should be declarated as following  format if you would not modified it's argment :
   char*/void funcion(const char* s1 ,const char* s2,.... )
3. if you have to give it to a string to the argment of a function , do as case "#if 0"or the comment I show above

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