encrypt.c

加密算法

/*
 *  Name:    $RCSfile$
 *
 *  Version: $Revision$
 *
 *  Created by: chensd
 *
 *  Purpose: This is a C language practice program
 *
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 *  Copyright (c) $Date$ Unication Co., Ltd.
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*/

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

const char dataValue[10] = {'7','8','9','0','1','2','3','4','5','6'};

/*
*  Name:       main
*
*  Purpose:    program entry
*
*  Params:     refer to the usage
*
*  Return:     >0 - succeed
*              -1 - met error
*
*  Note:       none
*
*/
int main(int argc, char**argv)
{
    char value[10];
    char charData[4];
	int intData[4];
    int temp;
    int strLength;
    int i;
    char *p;

	/*input the value*/
    printf( "Please input four integer:\n" );
	gets(value);
	
	/*judge the value have four character*/
	strLength = strlen(value);
    if(strLength != 4){
		printf("The input number is wrong!\n");
		return -1;
    }

	/*judge the value is number*/
    p = value;
    while(*p != '\0'){
		if(isdigit(*p) == 0){
			printf("The input number is wrong!\n");
			return -1;
		}
        p++;
    }

	/*search the corresponding character*/
	for(i=0; i<4; i++){
		intData[i] = value[i]-'0';
		charData[i]=dataValue[intData[i]];
	}

	/*change the number position*/
	temp = charData[0];
	charData[0] = charData[2];
	charData[2] = temp;

	temp = charData[1];
	charData[1] = charData[3];
	charData[3] = temp;
	  
	/*output the result*/
	printf("The encrypt result is:\n");
    for(i=0; i<4; i++){
		printf("%c", charData[i]);
	}
    printf("\n");

	return 0;
}