Program to print out the letters present in one word and absent in the other.

If you have any doubts, please do ask.

#include<stdio.h>
main()
{
    int i,j,flag=0;
char name1[10],name2[10];
scanf("%s",name1);
scanf("%s",name2);
for(i=0;i<strlen(name2);i++)
{
for(j=0;j<strlen(name1);j++)
{
if(name2[i]==name1[j])
flag=1;
}
if(flag==0)
{printf("%c",name2[i]);

}
else
    flag=0;
}}

Program to print out numbers separated by stars with the occurrence defined by the number printed.

This will print out something like this
1
2*2
3*3*3
4*4*4*4
and then the reverse image.
If you have any doubt, please do ask.

#include<stdio.h>
main()
{
int i=1,j=2,z=4,k;
printf("%d\n",i);
for(k=0;k<3;k++)
{
for(i=2;i<z-1;i++)
{
printf("%d*",j);
}
printf("%d\n");
j++;
z++;
}
j=4;
for(k=0;k<3;k++)
{
for(i=2;i<z-2;i++)
{
printf("%d*",j);
}
printf("%d\n");
j--;
z--;
}
printf("%d",1);
}

String reversal without string.h

This is a program to reverse a string without the string.h header. If you have any doubts, please do ask.

#include<stdio.h>
main()
{
int i,count=0,j=0;
char string[10],final[10];
scanf("%s",string);
for(i=0;string[i]!='\0';i++)
count++;
count--;
for(i=count;i>=0;i--)
{
final[j]=string[i];
j++;
}
final[j]='\0';
printf("%s",final);
}

Decrypting a message program

Feel free to use it, modify it or anything.

Try using the input

y!sr@xo#dt$pa%or^ko*vb(da&ql

You'll get the output laboratory

I've wrote in the comments what each function does. According to that, modify it to make a suitable input

#include <stdio.h>

#include <string.h>

char string[50],t;

int l,k;

main()

{

int i,j;

  

  gets(string);

   printf(" string is %s\n",string);

    l=strlen(string);

    k=l;

    letsreverse();

}

letsreverse() //function reverses a string

{

    

int i=0,j,q;

char *ptr;

ptr=string; 

q=l;

q--;

for(i=0;i<=(l/2)-1;i++)

  {

 t=*(ptr+i);

 *(ptr+i)= *(ptr+q);

 *(ptr+q)=t;

 q--;

 }

 printf("Reverse string is %s\n",string);

 wedontlikejunk();

}

wedontlikejunk()     // kills off junk

 {

    int i=0,z,c=0,x;

    char clean[20];

    for(x=0;x<k;x++)

    {

         if(string[c] >= 'a' && string[c] <= 'z')

         {

         clean[i]=string[c];

         i++;

         }

         c++;

         

    }

    clean[i]='\0';

    printf("semi string is %s\n",clean);

    for(i=0;clean[i]!='\0';i++)

    string[i]=clean[i];

    string[++i]='\0';

    letskillsomeletters();

}

letskillsomeletters()     //kills alternate letters

{

    int i=0,z;

    char final[20];

    for(z=(10%10);z<k;z++)

    {

        final[i]=string[z];

        i++;

        z++;

        

    

    }

    printf("Final string is %s\n",final);

}

IP address program

Really short C program to print out your ip address. Run it as an .exe. 

#include<stdlib.h>

main()
{
system("C:\\Windows\\System32\\ipconfig");
}

Decimal to Binary Program

Simple program to Convert a decimal number to binary. If you have doubts, let me know

#include <stdio.h>
main()
{
int num,count,temp;
printf("Enter the number");
scanf("%d",&num);
for(count=31;count>= 0;count--)
{
temp=num>>count;
if(temp&1)
printf("1");
else
printf("0");
}
}

Program to copy a file

C program to copy file. If you have any doubts, let me know

#include <stdlib.h>

#include <stdio.h>
main()
{
   
FILE *source, *target;

char x, sourcef[100], targetf[100];
   printf("File to copy?");
     gets(sourcef);
   source=fopen(sourcef, "r"); 
   printf("Target File?");
      gets(targetf);
   target=fopen(targetf, "w");
       while((x=fgetc(source))!=EOF)
           fputc(x, target);
  printf("The file has been copied.");
}