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1.1 Afisare Recursiv: Stdio.h Stdlib.h

The document contains code for recursively printing numbers with decreasing steps and code for encrypting and decrypting messages. The recursive function takes in a number and step size and prints the number, decreases it by the step size, calls itself recursively, and then prints the number again. The encryption/decryption code defines functions to encrypt and decrypt messages by shifting each character by the corresponding character in a key. It takes in a message and key as strings, finds the lengths, generates a repeated key if it is shorter than the message, encrypts the message, and prints the encrypted output.

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Bogdan Airinei
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41 views3 pages

1.1 Afisare Recursiv: Stdio.h Stdlib.h

The document contains code for recursively printing numbers with decreasing steps and code for encrypting and decrypting messages. The recursive function takes in a number and step size and prints the number, decreases it by the step size, calls itself recursively, and then prints the number again. The encryption/decryption code defines functions to encrypt and decrypt messages by shifting each character by the corresponding character in a key. It takes in a message and key as strings, finds the lengths, generates a repeated key if it is shorter than the message, encrypts the message, and prints the encrypted output.

Uploaded by

Bogdan Airinei
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as DOCX, PDF, TXT or read online on Scribd
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1.

1 Afisare recursiv

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

void recursion(int n, int pas)


{
if(n>=0)
{
printf(" %d ",n);
n-=pas;
recursion(n,pas);
printf(" %d ",n);
}
}
int main(void) {
int n=11;
int pas=2;
recursion(n, pas);
return 0;
}

1.2.

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

char* en;
char* dn;
char *message;
char *key;

int mystrlen(char *p)


{
int len=0;
while(*p!='\0')
{
len++;
*p++;
}
return len;
}
void encrypt(char message[], char key[], int dim)
{
for(int i=0;i<dim;i++)
{
en[i]=(message[i]+key[i])%26;
}
}

void decrypt(char message[], char key[], int dim)


{
for(int i=0;i<dim;i++)
{
dn[i]=(en[i]-message[i]+26)%26;
}
}
int main(void) {
message=(char*)malloc(sizeof(char));
key=(char*)malloc(sizeof(char));
//en=(char*)malloc(sizeof(char));
//dn=(char*)malloc(sizeof(char));
char en[100];
char dn[100];
char *k;
int dim=10;
printf("\nmessage=");
scanf("%s", message);
printf("\nkey=");
scanf("%s", key);
int nk=mystrlen(key);
int nm=mystrlen(message);
printf("\n nk=%d", nk);

int q=0, l=0;


while(q!=nm) //cat timp dim key e mai mica decat dim mesaj
{
if(l<nk)
{
k[q++]=key[l++];
}
else
{
l=0;
}
}
printf("\ngenerated key= %s", k);

encrypt(message, k, nm);
//decrypt(message, k, nm);

printf("\n encrypt=%s", en);


//printf("\n decrypt=%s", dn);

return 0;
}

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