c - 如何使用 C 显示数组中每个字母字符的出现次数？

Question

我正在尝试使用 ANSI C 编写一个小型应用程序。该应用程序应该使用指针打印出字符数组中每个字母的出现次数。

我的主文件:

#include "alphaStats.h"

int main(void) {

    int ABStats[26] = { 0 };

    char *pAr = Ar;
    int *pABStats = ABStats;

    GetFrequency(pAr,pABStats);
    DisplayVHist(pABStats,ALPHABET_SIZE);

    return EXIT_SUCCESS;

}

alphaStats.h 文件:

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include "alphaStats.c"

#define ALPHABET_SIZE 26

char Ar[] = {"All Gaul is divided into three parts, one of which the Belgae inhabit, the Aquitani another, those who in their own language are called Celts, in our Gauls, the third. All these differ from each other in language, customs and laws. The river Garonne separates the Gauls from the Aquitani; the Marne and the Seine separate them from the Belgae. Of all these, the Belgae are the bravest, because they are furthest from the civilization and refinement of [our] Province, and merchants least frequently resort to them, and import those things which tend to effeminate the mind; and they are the nearest to the Germans, who dwell beyond the Rhine , with whom they are continually waging war; for which reason the Helvetii also surpass the rest of the Gauls in valor, as they contend with the Germans in almost daily battles, when they either repel them from their own territories, or themselves wage war on their frontiers. One part of these, which it has been said that the Gauls occupy, takes its beginning at the river Rhone ; it is bounded by the river Garonne, the ocean, and the territories of the Belgae; it borders, too, on the side of the Sequani and the Helvetii, upon the river Rhine , and stretches toward the north. From 'Caesar's Conquest of Gaul', Translator. W. A. McDevitte. Translator. W. S. Bohn. 1st Edition. New York. Harper & Brothers. 1869. Harper's New Classical Library. Published under creative commons and available at http://www.perseus.tufts.edu/hopper/text?doc=Perseus:text:1999.02.0001"};

int GetFrequency(char*,int*);
void DisplayVHist(int*,int);

alphaStats.c 文件:

int GetFrequency(char *pAr, int *pABStats) {
    for (; pAr != '\0'; pAr++) {
        char c = *pAr;
        if (!isalpha(c)) continue;

        pABStats[(int)(toupper(c) - 'A')]++;
    }
    return 0;
}

void DisplayVHist(int *pABStats, int size) {
    int i;
    for (i = 0; i < size; i++) {
        printf("'%c' has %2d occurrences.\n", i + 'a', *pABStats++);
    }
}

我需要使用指针来计算 Ar[] 中每个字符出现的次数(即使用 pAr 和 pABStats)。运行上述代码时出现段错误。

有人知道为什么我的代码无法运行，并且可以帮助我完成编码吗？谢谢。

Answer 1

你错过了一个*。

for (; pAr != '\0'; pAr++) {
//    ^ need a *

其他评论:

#include 通常应该在 .c 文件中，除非您需要在 header 中使用类型或它们中的某些内容。此外，

#include "alphaStats.c"

永远不要包含 .c 文件。立即编译所有内容(gcc foo.c bar.c -o program)或(更频繁地)使用目标文件(gcc -c foo.c; gcc -c bar.c; gcc foo.o bar.o -o 程序)。所有这些 gcc 都应该启用警告 (-Wall -Wextra -pedantic)，在示例中省略它们会更清楚。

接下来，

char Ar[] = {"..."};

不确定为什么会编译，但你应该去掉大括号。字符串已经是 char[]。
此外，它应该在一个 C 文件中，如果你需要它在另一个文件中，请将 extern char Ar[] 放在标题中。

最后，花时间了解如何使用 gdb 是值得的。