意外的行为与strcpy和数组

Question

我正在写一个简单的字符串替换函数，我有一个相当有趣的错误。不应该strcpy只是覆盖buf \ streamBuf值？它如何连接数组？

int main() 
{ 
    char buf[512]; 
    strcpy(buf, "Test\nInput\nHere\n"); 

    char fromCh[2] = "\n"; 
    char toCh[4] = "\\n "; 
    stripChars(buf, fromCh, toCh); 
    printf("Here's your buf: %s", buf); 
    return 0; 
} 

void stripChars(char *streamBuf, char* fromCh, char *toCh){ 
     char strTemp[512]; 
     int i=0; 
     int iLenFrom = strlen (fromCh); 
     int iLenTo = strlen (toCh); 
     while (*streamBuf) 
     { 
      if (strncmp (streamBuf, fromCh, iLenFrom) == 0) 
      { 
       strncpy (&(strTemp[i]), toCh, iLenTo); 
       i += iLenTo; 
       streamBuf += iLenFrom; 
      } 
      else 
      { 
       strTemp[i++] = *streamBuf; 
       streamBuf++; 
      } 
     } 
    strTemp[i] = '\0'; 
    strcpy(streamBuf, strTemp); 

    printf("Here's your strTemp: %s \n", strTemp); 
    printf("Here's your streamBuf: %s \n", streamBuf); 
} 

，这里是我的输出

Here's your strTemp: Test\n Input\n Here\n 
Here's your streamBuf: Test\n Input\n Here\n 
Here's your buf: Test 
Input 
Here 
Test\n Input\n Here\n 
Process finished with exit code 0 

Answer 1

为什么它加到阵列？

这是因为你正在改变streamBuf指向函数的位置。

跟踪streamBuf所指向的原始位置，并在函数结束时使用它。

void stripChars(char *streamBuf, char* fromCh, char *toCh) 
{ 
    char* originalPointer = streamBuf; 

    ... 

    streamBuf = originalPointer; 
    strcpy(streamBuf, strTemp); 

    printf("Here's your strTemp: %s \n", strTemp); 
    printf("Here's your streamBuf: %s \n", streamBuf); 
} 

Answer 2

这里

streamBuf += iLenFrom; 

这里

streamBuf++; 

你改变streamBuf

因此它将不再等于main中的buf。

所以对数据的更改指向streamBuf不再相同，变化的数据指向buf

如果你想看看会发生什么，你可以添加指针值的印刷品，如：

printf("buf is at %p\n", (void*)buf); 
stripChars(buf, fromCh, toCh); 

和

void stripChars(char *streamBuf, char* fromCh, char *toCh){ 
    printf("streamBuf is at %p\n", (void*)streamBuf); 
    .... 
    .... 
    printf("streamBuf is at %p\n", (void*)streamBuf); 
    printf("Here's your streamBuf: %s \n", streamBuf); 
}