c - C 中的数组访问错误

Question

我的代码中不断出现 valgrind 错误，我不知道如何修复它。 :/这个想法是，无论输入中 2 个或更多单词/字母之间有多少制表符/空格，在输出中它都应该只有一个空格。例如:

a    b   c d -> a b c d

代码:

char* echo(char* in) {
    char buffer[256];
    int incounter=0, buffcounter=0;

    while(incounter<(strlen(in))) {
        if(in[incounter] == ' ' || in[incounter] == '\t') incounter++;
        else if(in[incounter] != ' ' && in[incounter] != '\t') {
            while(in[incounter] != ' ' && in[incounter] != '\t') {
                buffer[buffcounter] = in[incounter];  //53
                incounter++;
                buffcounter++;              
            }           
            buffer[buffcounter] = ' ';
            buffcounter++;
        }
    }
    char* out = buffer;
    return out;
}

错误:

==20521== Conditional jump or move depends on uninitialised value(s)
==20521==    at 0x4010B4: echo (hhush.c:53)
==20521==    by 0x4021CA: readCommand (hhush.c:327)
==20521==    by 0x402538: main (hhush.c:371)
==20521==  Uninitialised value was created by a stack allocation
==20521==    at 0x402017: readCommand (hhush.c:301)
==20521== 
==20521== Conditional jump or move depends on uninitialised value(s)
==20521==    at 0x4010CE: echo (hhush.c:53)
==20521==    by 0x4021CA: readCommand (hhush.c:327)
==20521==    by 0x402538: main (hhush.c:371)
==20521==  Uninitialised value was created by a stack allocation
==20521==    at 0x402017: readCommand (hhush.c:301)

我现在就是这样，还是一样的错误

char* echo(char* in,char* buffer){
    size_t inlen=strlen(in);
    int incounter=0,buffcounter=0;
    while(incounter<inlen){
        if(in[incounter]==' '||in[incounter]=='\t')incounter++;
        else{
            while(in[incounter]!=' '&&in[incounter]!='\t'){
                buffer[buffcounter]=in[incounter];
                incounter++;
                buffcounter++;              
            }           
            buffer[buffcounter]=' ';
            buffcounter++;
        }   
    }
    return buffer;
}

我称它为:

char input[256];
fgets(input,sizeof(input),stdin);
...
char buffer[256];
printf("%s\n",echo(input,buffer));

Answer 1

 char* out=buffer;
 return out;
}

不要返回指向具有自动存储持续时间的数组的指针(此处为 buffer 数组)。如果访问指针值，它会调用未定义的行为，因为当退出声明它们的 block 时自动对象被丢弃(这里是 echo 函数返回时)。