崩盘的getchar

Question

主要功能代码如下：

#define MEM_INCR 20  

int main(void) 
{ 
char *str = NULL, **s_words = NULL, *temp = NULL, *tempbuf = NULL; 
int wordcount = 0, i, length = 0, memo = 0; 

do 
{ 
    if(length >= memo) 
    { 
     memo += MEM_INCR; 
     if(!(tempbuf = realloc(str, memo))) 
     { 
      printf("Memory allocation failed."); 
      return 1; 
     } 
     str = tempbuf;; 
    } 
} 
while((str[length++] = getchar()) != '\n'); 
str[--length] = '\0'; 

wordcount = word_count(str); 

s_words = malloc(wordcount); //Allocate sufficient memory to store words 
for(i = 0; i < wordcount; i++) //Now allocate memory to store each word 
    s_words[i] = calloc(MAX_LENGTH, sizeof(char)); //Use this function in order not to have unfilled space 
segment(str, s_words); //Segment the string into words 

printf("Words sorted: \n"); //Output the message 
for(i = 0; i < wordcount; i++) //Short the words from the shortest to the longest 
{ 
    if(strcmp(s_words[i], s_words[i + 1]) > 0) //Check if the first word is longer than the second 
    { 
     temp = s_words[i]; //Store the first address in temp 
     s_words[i] = s_words[i + 1]; //Assign the successive address to the previous one 
     s_words[i + 1] = temp; //Assign the first to the successive 
     temp = NULL; //Ensure NULL in order to avoid leaks 
    } 
    printf("%s", s_words[i]); //Output the words ordered 
} 
return 0; 
} 

程序工作正常，如果我提供给它一个固定的字符串，或者如果我用得到（）函数，但是当我使用上面的代码为了能够接收任意长度的字符串，我得到了崩溃。存在的函数正常工作，唯一的问题是使用getchar时。你能帮我吗？

在此先感谢！

Answer 1

您写道：

do { 
    /* ... */ 
} while((str[length++] = getchar()) != '\n'); 

但getchar()的定义是int getchar(void)。 getchar()函数被定义为返回一个int有很好的理由 - 它需要某种方式告诉你没有更多的输入。这种方式是返回-1 - 在您的代码中，如果发生这种情况，那么您的循环会消失，gethchar()只会一直返回-1，并且一直在分配内存，直到它全部消失。

编辑：一个可能的解决办法：getchar`为`int`的`

int c; 

do { 
    /* ... */ 
    c = getchar(); 
    if (c < 0) c = '\0';  /* one idea, handle this case as you see fit */ 
    if (c == '\n') c = '\0'; 
} while ((str[length++] = c) != '\0');