Question

所以这应该是一个协调程序，它从文本文件中抓取单词。我正在尝试使用结构来存储字符串，以及文本文件中单词出现的次数。我还想将struct对象放入一个结构数组中，因为我需要按字母顺序对单词进行排序。但是，我在createStruct函数中遇到了分段错误。我知道问题在于我对指针的知识有限以及通过引用传递。我几天来一直在搞乱createStruct和compareStruct，它只是没有点击。

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

typedef struct word{
    char *wordArr;
    int wordCount;
}word;


char *makeLowerCase(char word[]);
char *removeFirstChar(char word[]);
char *removeLastChar(char word[]);
void createStruct(struct word wordObj, char word[]);
void structCompare(struct word wordObj, struct word objArr[]);

int main(int argc, char * argv []) {

char buff[] ="@#Hello$$$$$"; //hard coded, will grab words from a .txt file
struct word newWord = {.wordArr = NULL, .wordCount = 0};
struct word structArray[500];      

makeLowerCase(buff);                 
removeFirstChar(buff);               
removeLastChar(buff);                
createStruct(newWord, buff);         
structCompare(newWord, structArray);

//trying to print from the array
printf("%s %d", structArray->wordArr, structArray->wordCount);


return 0;
}

char *makeLowerCase(char grabbedWord[]) {
    int i;
    size_t wordLength = strlen(grabbedWord);

    for(i = 0; i < wordLength; i++) {
        grabbedWord[i] = tolower(grabbedWord[i]);
    }
return grabbedWord;
};

char *removeFirstChar(char inputWord[]) {
    int i = 0;
    size_t length = strlen(inputWord);

    if (!isalnum(inputWord[i])) {
        i++;
        strncpy(inputWord, &inputWord[i], length);
        return removeFirstChar(inputWord);
    }

return inputWord;
};

char *removeLastChar(char inputWord[]) {
    size_t length = strlen(inputWord);

    if (!isalnum(inputWord[length - 1])) {
        inputWord[length - 1] = 0;
        return removeLastChar(inputWord);
    }

return inputWord;
};


void createStruct(struct word wordObj, char string[]) {
    strcpy(wordObj.wordArr, string);
    wordObj.wordCount = 1;
};

void structCompare(struct word obj, struct word structArr[]) {

    int i;

    for(i = 0; i < sizeof(structArr); i++) {

        if(structArr[i].wordCount == 0) {
        strcpy(structArr[i].wordArr, obj.wordArr);
        structArr[i].wordCount = obj.wordCount;
        }
        else if(strcmp(structArr[i].wordArr, obj.wordArr) == 0) {
            structArr->wordCount++;
        }
        else {
            strcpy(structArr[i].wordArr, obj.wordArr);
            structArr[i].wordCount = obj.wordCount;
        }
    }
};

Answer 1

由于 NULL 指针，您获得segmentation fault。

要复制字符串，请使用strcpy(char *dest, char *src)。但需要分配dest。在您的情况下，只是 NULL ;

所以这就是你需要做的事情：

// Add a \0 to the end of a string so you know when to stop.
char buff[] ="@#Hello$$$$$\0";

// Allocate the char array so you know where to copy it. I allocate it by default to 500, change this based on your needs.
struct word newWord = {.wordArr = (char *)malloc(sizeof(char) * 500), .wordCount = 0};

如果直接将结构传递给函数，则会传递copy，因此函数中的任何更改都不会在函数外部看到。因此，您需要将pointer传递给struct而不是实际的struct。

C结构，字符串和分段错误

1 个答案: