encrypt.c.bak

加密算法

/*
 *  Name:    $RCSfile$
 *
 *  Version: $Revision$
 *
 *  Created by: chensd
 *
 *  Purpose: This is a C language practice program
 *
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 *  DO NOT COPY
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 *  Copyright (c) $Date$ Unication Co., Ltd.
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 *  All rights reserved
*/

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

/*
*  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];
    int data[4];
    int num_data;
    int temp;
    int strLength;
    int i;
    char *p;

	/*input the value*/
    printf( "Please input four integer:\n" );
    if(scanf("%s", value) != 1){
		printf("bad input!\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++;
    }

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

	/*pick-up each number*/
	num_data = atoi(value);
	data[0] = num_data/1000;
	data[1] = num_data%1000/100;
	data[2] = num_data%1000%100/10;
	data[3] = num_data%1000%100%10;
	
    /*add 7 */
	for(i=0; i<4; i++){
		data[i] += 7;
		data[i] = data[i]%10;
	}

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

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

	return 0;
}