Question

我不久前接受了编程。我试图创建一个函数来从用户那里获取一个字符串（为了实践起见）。我的getString（）函数似乎做了它的工作，但如果输入字符串太长（超过17个字符是特定的），一个奇怪的＆＃34;？＆＃34;被添加到我的字符串中。不知道我搞砸了哪里，我有时候一直在调查它，这里是我的代码

char* getString(void)
{
    /* how large is the buffer */
    unsigned int capacity = 32;
    /* growable buffer to store string */
    char* buffer = malloc(capacity * sizeof(char));
    if (buffer == NULL)
    {
        return NULL;
    }
    /* how many characters are actually there in the buffer */
    unsigned int n = 0;
    int c; // character read or EOF

    while((c = fgetc(stdin)) != '\n' && c != EOF)
    {
        // if there's enough space in buffer -> store c into buffer, continue to next loop
        if (n + 1 >= capacity)
        {
            capacity *= 2;
            char* temp = realloc(buffer, capacity * sizeof(char));
            if(temp == NULL)
            {
                free(buffer);
                return NULL;
            }
            buffer = temp;
        }
        // store c to reallocated buffer
        buffer[n++] = c;
    }

    if (n == 0 && (c == EOF))
    {
        return NULL;
    }

    // terminate string with '\0'
    buffer[++n] = '\0';
    puts(buffer);
    // remove blank space after '\0'
    buffer = realloc(buffer, (n+1) * sizeof(char));

    // return buffer
    return buffer;
}

测试程序：

Pls gimme a string
12345678901234567890
You gave me this string: "12345678901234567890?", which is 21 chars long

Answer 1

问题在于：

buffer[++n] = '\0';

当循环结束时，n的值已经正确，并且您应该放置终止符。再次递增它会使终结器超出您读入内存的数据。

自定义输入功能，怪异的＆＃39;？＆＃39;附加在字符串的末尾

1 个答案: