c - C 中的字符串排序

Question

嗯，我正在尝试按 C 语言文件中的字母顺序对字符串进行排序，但我的程序不起作用。我认为动态数组的内存分配错误，但我找不到它。

        #include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define buflen 42
int comp(const void * a, const void * b) {
    const char *arraya = *(const char**)a;
    const char *arrayb = *(const char**)b;

    return strcmp(arraya, arrayb);
}
char* getarray(FILE *input)
{
    char buffer[buflen];
    char* result = NULL;
    size_t chargot = 0;
    size_t fact = 0;
    size_t wasinarray = 0;
    while (fgets(buffer, buflen, input))
    {
        chargot = strlen(buffer);
        fact += chargot;
        if (fact >= wasinarray)
        {
            wasinarray += buflen;
            result = realloc(result, wasinarray);
            strcat(result, buffer);
        }
        if (buffer[chargot - 1] == '\n')
            break;
    }
    if (ferror(stdin))
    {
        if (result)
            free(result);
        return NULL;
    }
    return result;
}


int main() {
    char **strarray = NULL;
    int i = 1, strcount = 0;
    char* strline;
    FILE *input, *output; 
    input = fopen("input.txt", "r");
    output = fopen("output.txt", "w");
    strarray = (char**)malloc(i * sizeof(char*));
    while (strline = getarray(input) != NULL)
    {
        strarray[strcount] = strline;
        strarray = (char**)realloc(strarray, (i + 1) * sizeof(char*));
        strcount++;
        i++;
    }
    qsort(strarray, strcount, sizeof(char**), comp);
    for (i = 0; i < strcount; i++)
    {
        fprintf(output, "%s", strarray[i]);
        free(strarray[i]);
    }

    free(strarray);
    free(strline);
    close(output);
    close(input);
    return 0;
}

输入和输出必须是这样的

输入:

 dfsdfds
 asfsdfds
 badgfdgfd
 csdfdsgfd

输出:

 asfsdfds 
 badgfdgfd
 csdfdsgfd
 dfsdfds

Answer 1

像这样修复:

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

#define buflen 42

int comp(const void * a, const void * b) {
    return strcmp(*(const char**)a, *(const char**)b);
}

char* getarray(FILE *input){
    char buffer[buflen];
    char* result = NULL;
    size_t chargot = 0;
    size_t fact = 0;

    while (fgets(buffer, buflen, input)){
        chargot = strlen(buffer);
        result = realloc(result, fact + chargot + 1);
        memcpy(result + fact, buffer, chargot + 1);
        fact += chargot;
        if (buffer[chargot - 1] == '\n')
            return result;
    }
    return NULL;
}

int main(void){
    char **strarray = NULL;
    int i = 0, strcount = 0;
    char* strline;
    FILE *input, *output;

    input = fopen("input.txt", "r");
    output = fopen("output.txt", "w");

    while ((strline = getarray(input)) != NULL){
        strarray = realloc(strarray, (i + 1) * sizeof(char*));
        strarray[i++] = strline;
    }

    qsort(strarray, (strcount=i), sizeof(char*), comp);
    for (i = 0; i < strcount; i++){
        fprintf(output, "%s", strarray[i]);//!!Input line includes always newline
        free(strarray[i]);
    }

    free(strarray);
    fclose(output);
    fclose(input);
    return 0;
}