Mono Alphabetic Encryption DCN

This program is for implementing Mono-Alphabetic Encryption . This is a part of Mumbai University MCA Colleges Data Communication and Networking MCA Sem 4

#include<stdio.h>

#include<conio.h>

void main()

{

            char str[100],ckey[3];

            int encr[100],key;

            int i,j,k,tmp;

            clrscr();

            printf("Enter String : ");

            gets(str);

            printf("Enter key : ");

            gets(ckey);

            k=ckey[0];

            if(k>=49 && k<=58)

            {

                        key=0;

                        k=strlen(ckey);

                       

for(i=0;i<k;i++)

                        {

                                    tmp=ckey[i]-48;

                                    tmp=tmp%10;

                                    key=(key*10)+tmp;

                        }

            }

            if(k>=65 && k<=90)

            {

                        key=1;

                        tmp=65;

                        while(tmp!=k)

                        {

                                    key++;

                                    tmp++;

                        }

            }

            if(k>=97 && k<=123)

            {

                        key=1;

                        tmp=97;

                        while(tmp!=k)

                        {

                                    key++;

                                    tmp++;

                        }

            }

            for(i=0;str[i]!='\0';i++)

            {

                        if(str[i]>=65 && str[i]<=90)

                        {

                                    encr[i]=str[i]+key;

                                    if(encr[i]>90)

                                    {

                                                j=encr[i]-90;

                                                encr[i]=64+j;

                                     }

                        }

                        else

                        {

                                    encr[i]=str[i]+key;

                                    if(encr[i]>122)

                                    {

                                                j=encr[i]-122;

                                                encr[i]=96+j;

                                    }

                        }

                        printf("%c",encr[i]);

            }

getch();

}

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