更改函數中指針的值

Question

我想更改函數中變量的值。 我的代碼是這樣的：

void change(char *buf){ 
    char str = "xxxxxxx"; 
    *buf = &str; 
} 
int main(){ 
    char *xxx = NULL; 
    change(xxx); 
} 

，當我和Valgrind的調試，它說：

==3709== Invalid write of size 1 
==3709== at 0x80483CA: change (test.c:5) 
==3709== by 0x80483E5: main (test.c:10) 
==3709== Address 0x0 is not stack'd, malloc'd or (recently) free'd 
==3709== 
==3709== 
==3709== Process terminating with default action of signal 11 (SIGSEGV) 
==3709== Access not within mapped region at address 0x0 
==3709== at 0x80483CA: change (test.c:5) 
==3709== by 0x80483E5: main (test.c:10) 

誰能幫助我？我用C是新....

Answer 1

使用指針的指針：

void change(char **buf) 
{ 
    *buf = "xxxxxxx"; 
} 

int main(void) 
{ 
    char *xxx = NULL; 
    change(&xxx); 
}