如何在 C 中进行 char* 数组元素交换？

Question

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

char* temp=" ";
char char_array[4][100]= {"-11111","-1111","-1110","-1112"};

void str_swap(char** a,char** b);

int main(int argc,char* argv[]) {
    int j=0,n=4;

    printf("BEFORE str_swap(&char_array[0],&char_array[2]);\n");

    for (j=0; j<n; j++) {
        printf("char_array[%d] = %s\n",j,char_array[j]);
    }


    str_swap(&char_array[0],&char_array[2]);


    printf("AFTER str_swap(&char_array[0],&char_array[2]);\n");

    for (j=0; j<n; j++) {
        printf("char_array[%d] = %s\n",j,char_array[j]);
    }

    return 0;
}

void str_swap(char** str1,char** str2) {
    temp = *str1;
    *str1 = *str2;
    *str2 = temp;
}

你好all:I想在C中做char*数组元素交换，上面是我的代码。但是我没有改变下面的输出shown.Am我在这里遗漏了什么？谢谢你的帮助提前。

BEFORE str_swap(&char_array[0],&char_array[2]);
char_array[0] = -11111
char_array[1] = -1111
char_array[2] = -1110
char_array[3] = -1112
AFTER str_swap(&char_array[0],&char_array[2]);
char_array[0] = -11111 //should be -1110
char_array[1] = -1111
char_array[2] = -1110 //should be -11111
char_array[3] = -1112

进程返回 0 (0x0) 执行时间：0.359 秒
按任意键继续。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAXLEN 1002
char *char_array[MAXLEN];
void str_swap(char const** str1,char const** str2);
int my_compare_func(int,int);
void bubble_sort(int,int(*compare_func)(int,int));

int main(int argc,char* argv[]) {
    int n=0,i=0,j=0;
    while(scanf("%d",&n)==1) {
        i=n;
        while(i--) {
            scanf("%s",&char_array[i]);
        }
        printf("BEFORE BULLE SORT\n");
        for (j=0; j<n; j++) {
            printf("j = %d\n",j);
            printf("char_array[%d] = %s\n",j,&char_array[j]);
            //printf("char_array[%d] = %s\n",j,char_array[j]);
        }
        bubble_sort(n,my_compare_func);
        printf("AFTER BULLE SORT\n");
        for (j=0; j<n; j++) {
            printf("j = %d\n",j);
            printf("char_array[%d] = %s\n",j,&char_array[j]);
            //printf("char_array[%d] = %s\n",j,char_array[j]);
        }    
        system("PAUSE"); 
    }  
    return 0; 
}

int my_compare_func(int x,int y) {
    int i=0,res = 0,len_strx=0,len_stry=0;
    len_strx = strlen(char_array[x]);
    len_stry = strlen(char_array[y]);
    if(char_array[x][0]=='-') {
        if(char_array[y][0]=='-') {
            if(len_strx>len_stry) {
                res = -1;
            }else if(len_strx<len_stry) {
                res = 1;
            }else if(len_strx==len_stry) {
                i=1;
                while((char_array[x][i]==char_array[y][i])&&(char_array[x][i]!='[=11=]')&&(char_array[y][i]!='[=11=]')) {
                    ++i;
                }
                if(i==len_strx) {
                    res = 0;
                }else if(char_array[x][i]<char_array[y][i]){
                    res = 1;
                }else if(char_array[x][i]>char_array[y][i]) {
                    res = -1;
                }
            }         
        }else if((char_array[y][0]>='0'&&char_array[y][0]<='9')||char_array[y][0]=='+'){
            res = -1;        
        }
    }else if((char_array[x][0]>='0'&&char_array[x][0]<='9')||char_array[x][0]=='+') {
        if((char_array[y][0]>='0'&&char_array[y][0]<='9')||char_array[y][0]=='+'){
            if(len_strx>len_stry) {
                res = 1;
            }else if(len_strx<len_stry) {
                res = -1;
            }else if(len_strx==len_stry) {
                i=0;
                while(char_array[x][i]==char_array[y][i]&&char_array[x][i]!='[=11=]'&&char_array[y][i]!='[=11=]') {
                    ++i;
                }
                if(i==len_strx) {
                    res = 0;
                }else if(char_array[x][i]<char_array[y][i]){
                    res = -1;
                }else if(char_array[x][i]>char_array[y][i]){
                    res = 1;
                }
            }
        }else if(char_array[y][0]=='-') {
            res = 1;
        }
    }
    return res;    
}

void str_swap(char const** str1,char const** str2) {
    char const* temp = *str1;
    *str1 = *str2;
    *str2 = temp ; 
}

void bubble_sort(int n,int(*compare_func)(int x,int y)) {
    int i=0,j=0,flag=1;
    for(i=n-1; (i>0)&&(flag==1); --i) {
        flag=0;
        for(j=0; j<i; ++j) {
            if(compare_func(j,j+1)>0) {
                str_swap(&char_array[j],&char_array[j+1]);
                flag = 1;
            }
         }  
         if(!flag) {
             break;
         }
    }
}

Thank you for all the answers.Your response is very fast.In fact I am trying to solve the basic online judge problem.Check it here:(in mandarin) http://zerojudge.tw/ShowProblem?problemid=a528
Basically it's a sorting problem with string storing big number(both positive and negative).Sorry for posting such huge amount lines of code.fast.My new problem is that while I have my code running to the line:
//printf("char_array[%d] = %s\n",j,&char_array[j]);
printf("char_array[%d] = %s\n",j,char_array[j]);
then the console application crashed!I tried some approach like the commented line(that is,set the %s part in printf() function to be &char_array[j]).It works fine but contradicts my knowledge about arguments > of printf().Can anyone explain this for me?Thanks :)

Answer 1

您提供的代码无法编译，因为 &char_array[0] 的类型不是 str_swap 函数期望得到的 char**。基本上你可以通过进行这些更改来实现你想要的：

#include <string.h>

char temp[100];
...
void str_swap(char* a,char* b);
...
str_swap(char_array[0],char_array[2]);//you don't need to use the & operator here
...
void str_swap(char* str1,char* str2) 
{
   strncpy(temp,str1,100);//copy the first to temp
   strncpy(str1,str2,100);//copy the second to the first
   strncpy(str2,temp,100);
}

Answer 2

是的，您在这里遗漏了一些东西。 char [4][100] 是数组数组，不是指针数组。你的函数需要指针的地址，而不是数组的地址（数组不是指针）。

将您的数组更改为 const char* 的数组（指向常量字符数据的指针），并且您的函数正确地将指针交换为该类型的指针将解决您的问题。

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

char const *char_array[4] = {"-11111","-1111","-1110","-1112"};

void str_swap(char const ** str1,char const ** str2);

int main(int argc,char* argv[])
{
    int j=0,n=4;

    printf("BEFORE str_swap(&char_array[0],&char_array[2]);\n");

    for (j=0; j<n; j++) {
        printf("char_array[%d] = %s\n",j,char_array[j]);
    }


    str_swap(&char_array[0], &char_array[2]);


    printf("AFTER str_swap(&char_array[0],&char_array[2]);\n");

    for (j=0; j<n; j++) {
        printf("char_array[%d] = %s\n",j,char_array[j]);
    }

    return 0;
}

void str_swap(char const ** str1, char const ** str2)
{
    char const *temp = *str1;
    *str1 = *str2;
    *str2 = temp;
}

输出

BEFORE str_swap(&char_array[0],&char_array[2]);
char_array[0] = -11111
char_array[1] = -1111
char_array[2] = -1110
char_array[3] = -1112
AFTER str_swap(&char_array[0],&char_array[2]);
char_array[0] = -1110
char_array[1] = -1111
char_array[2] = -11111
char_array[3] = -1112

你的原始代码运行s 是一个谜，因为我使用的 C 编译器都不允许你正在做的事情进行编译，更不用说运行.

Answer 3

要编译代码，您必须将矩阵更改为指向文字 c 字符串的指针数组，因此

char char_array[4][100]= {"-11111","-1111","-1110","-1112"};

必须

char *char_array[4]= {"-11111","-1111","-1110","-1112"};

您的代码应该是

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

char *char_array[]= {"-11111","-1111","-1110","-1112"};

#define ARRAY_SIZE  sizeof(char_array)/sizeof(char_array[0])

void str_swap(char** a,char** b);

int main() {
    size_t j=0;

    printf("BEFORE str_swap(&char_array[0],&char_array[2]);\n");

    for (j=0; j<ARRAY_SIZE; j++) {
        printf("char_array[%zu] = %s\n",j,char_array[j]);
    }

    str_swap(&char_array[0],&char_array[2]);


    printf("AFTER str_swap(&char_array[0],&char_array[2]);\n");

    for (j=0; j<ARRAY_SIZE; j++) {
        printf("char_array[%zu] = %s\n",j,char_array[j]);
    }

    return 0;
}

void str_swap(char** str1, char** str2) {
    char* temp;
    temp = *str1;
    *str1 = *str2;
    *str2 = temp;
}

输出将是

BEFORE str_swap(&char_array[0],&char_array[2]);
char_array[0] = -11111
char_array[1] = -1111
char_array[2] = -1110
char_array[3] = -1112
AFTER str_swap(&char_array[0],&char_array[2]);
char_array[0] = -1110
char_array[1] = -1111
char_array[2] = -11111
char_array[3] = -1112

如何在 C 中进行 char* 数组元素交换？

How to do char* array element swapping in C?

c

swap

pointers