Question

我在C中创建一个程序，它计算输入的每个单词中的字母数，然后将它们打印为直方图。我在这个程序中使用了很多for循环，我收到了以下错误：

letter_size_chart.c:35:37: error: expected expression
    for (i = maximum; i >= MIN_CHARS; --i)
                                    ^
letter_size_chart.c:38:27: error: expected expression
        for (j = MIN_CHARS; i <= MAX_CHARS; ++i)
                          ^
letter_size_chart.c:48:23: error: expected expression
    for (i = MIN_CHARS; i <= MAX_CHARS; i++) 
                      ^
letter_size_chart.c:50:23: error: expected expression
    for (i = MIN_CHARS; i <= MAX_CHARS; i++) 
                      ^
4 errors generated.

我的循环中有什么导致这些错误？这是我的代码：

/* 
    sorts input by size of words into a histogram
*/

#define EOF -1
#define MAX_CHARS 10    /* max number of chars allowed in a word */
#define MIN_CHARS

#include<stdio.h>
#include<ctype.h>

int main()
{
    int c, i, j, word_length, numbcountsize, maximum;
    int numbcount[MAX_CHARS];
    word_length = 0;

    while ((c = getchar()) != EOF)
    {
        if (isalpha(c))
            ++word_length;
        else 
            if (word_length != 0)
            {
                ++numbcount[word_length - 1];
                word_length = 0;
            }
    }

    maximum = numbcount[0];
    for (i = MIN_CHARS; i <= MAX_CHARS; i++)
        if (numbcount[i - 1] > maximum)
            maximum = numbcount[i];

    for (i = maximum; i >= MIN_CHARS; --i)
    {
        printf("%d |", i);
        for (j = MIN_CHARS; i <= MAX_CHARS; ++i)
        {
            if (j >= i)
                printf(" * ");
            else 
                printf("   ");
        }
        printf("\n");
    }
    printf("  | ");
    for (i = MIN_CHARS; i <= MAX_CHARS; i++) 
        printf("_");
    for (i = MIN_CHARS; i <= MAX_CHARS; i++) 
        printf("%d\n", i);
}

Answer 1

当你使用空字符串#define时，即

#define MIN_CHARS

它告诉预处理器从程序文本中删除 MIN_CHARS的所有提及。实际上，你的循环看起来像这样：

for (i =; i <= 10; i++)

这是无效的，因此C编译器拒绝它。

为MIN_CHARS提供值可解决此问题：

#define MIN_CHARS 2

在C

1 个答案: