Question

我真的不知道这是否是我问题的正确标题，但我会尝试解释我的问题：

我正在开发一个搜索所有字符串置换的程序，并将这些字符串保存在char**数组中。

一切看起来都不错，但是程序花费太多时间完成，这是因为realloc调用太多而且需要花费太多时间。我在这里谈论13700个电话：

for ( size_t i = 0; i < SIZE_2D; i++ ){ // SIZE_2D == 13700
    multi[i] = calloc(LINELENGTH, sizeof(char));
}

可以在一次通话中调用char**上的realloc吗？就像这里的例子：

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

int main(void){
    int *arr;
    unsigned int row = 5, col = 10;

    arr = malloc(sizeof *arr * row * col);
    if(arr == NULL){
        printf("Error, malloc\n");
        exit(3);
    }

    free(arr);
}

这是工作代码：

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

#define SIZE_2D 13700
#define LINELENGTH 8

void swap (char *x, char *y);
void permute(char *arr, char *ptr, size_t i, size_t n);
int compare(const void *a, const void *b);
void resizeBuffer ( char **arr, size_t length );
void resultFound( char **multi, char *buffer, size_t length );

//char multi[20240][50] = {0};

int main(void){
    char str[] = "abcdefg";
    char *arr = calloc(100000, sizeof(char));
    char *multi[14000];
    //char **multi = calloc(10240, sizeof(char*));

    for ( size_t i = 0; i < SIZE_2D; i++ ){
        multi[i] = calloc(LINELENGTH, sizeof(char));
    }

    permute( arr, str, 0, strlen( str ) );
    resizeBuffer ( &arr, strlen( arr ) + 1 );

    resultFound(multi, arr, strlen( arr ) );
    free( arr );

    for ( size_t i = 0; i < SIZE_2D; i++ ){
        free(multi[i]);
    }
}

void resultFound( char **multi, char *buffer, size_t length ){
    printf("ARR LENGTH = %zu\n", length);
    size_t i = 0;
    char *ptr = buffer;
    size_t p = 0;
    size_t a = 0;

    char *tmp = calloc(length + 1, sizeof(char));
    size_t count = 0;

    while ( i < length ){
        if ( ptr[i] == '\n' ){
            if ( count != 0){
                //printf("Line Found! <-> Line Length = %zu <-> TMP = %s\n",count, tmp);
                strcpy(multi[a++], tmp);
                memset(tmp, 0, length);
                count = 0;
                p = 0;
            }else{
                //printf("Empty Line Found, Ignore it\n\n");
            }
        }else{
            count++;
            tmp[p++] = ptr[i];
        }
        i++;
    }

    for (size_t l = 0 ; l < a ; l++ ){
        printf("Multi[%zu]\t=  %s\n",l , multi[l]);
    }

    free(tmp);
}

void swap (char *x, char *y){
    char temp;
    temp = *x;
    *x = *y;
    *y = temp;
}

void permute(char *arr, char *ptr, size_t i, size_t n){
    size_t j;
    static char prev[80] = "";
    if (i == n){
        if (strcmp(prev, ptr)) {
            strcat (arr, ptr);
            strcat (arr, "\n");
            strcpy(prev, ptr);
        }
    }else{
        for (j = i; j <= n; j++)
        {

            swap( (ptr + i), (ptr + j) );
            permute(arr, ptr, i+1, n);
            swap( (ptr + i), (ptr + j) );
        }
    }
}

void resizeBuffer ( char **buffer, size_t length ){
    *buffer = realloc(*buffer, (length)* sizeof(char) );
}

可以在一行中使用char **上的realloc吗？

0 个答案: