C Program Lab Exercise

I. SWAPPING OF TWO NUMBERS USING FUNCTION:

Program:

#include <stdio.h>
void swap(int, int);
int main()
{
    int x, y;
    x = 10;
    y = 20;
    swap(x, y);
    printf("Value of x and y after swap(x, y) in main()  : %d %d \n", x, y);
}

void swap(int a, int b)
{
    int t;
    printf("Value of a and b before exchange in swap()   : %d %d \n", a, b);
    t = a;
    a = b;
    b = t;
    printf("Value of a and b after exchange in swap()    : %d %d \n", a, b);

    return 0;
}

Output:

Value of a and b before exchange in swap()   : 10 20
Value of a and b after exchange in swap()    : 20 10
Value of x and y after swap(x, y) in main()  : 10 20

II. ARRAY USING POINTERS:

Program:

#include <stdio.h>
int main()
{
    int i, n;
    printf("Enter the size of the array : ");
    scanf("%d", &n);
    int *a[n];
    printf("Enter the elements : \n");
    for(i = 0; i < n; i++)
    {
        scanf("%d", &a[i]);
    }
    printf("\nThe given elements are \n");
    for(i = 0; i < n; i++)
    {
        printf("a[%d] = %d\n", i , *(a+i));
    }
    return 0;
}

Output:

Enter the size of the array : 2
Enter the elements :
10
15

The given elements are
a[0] = 10
a[1] = 15

III. LENGTH OF THE STRING:

Program:

#include <stdio.h>
#include <string.h>
int l(char *);
int main()
{
    int len;
    static char s1[] = "anand";
    len = l(s1);
    printf("Length of the string s1 : %d \n", len);

    return 0;
}

int l(char *ptr)
{
    int s = 0;
    while(*ptr != '\0')
    {
        s++;
        ptr++;
    }
    return s;
}

Output:

Length of the string s1 : 5

IV. STRING CONCATENATION:

Program:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define LENGTH 20
int main()
{
    char *s1, *s2, *s3, c;
    int i = 0, k = 0;
    s1 = malloc(LENGTH * sizeof(char));
    s2 = malloc(LENGTH * sizeof(char));
    s3 = malloc(2 * LENGTH * sizeof(char));
    printf("Enter the string s1 : ");
    scanf("%s", s1);
    printf("Enter the string s2 : ");
    scanf("%s", s2);
    i = strlen(s1);
    s3 = s1;
    while((c = *(s2 + k)) != '\0')
    {
        s3[i + k] = c;
        k++;
    }
    s3[i + k] = '\0';
    printf("The concatenated string : %s \n", s3);
    return 0;
}

Output:

Enter the string s1 : tamil
Enter the string s2 : nadu
The concatenated string : tamilnadu

V. FILE HANDLING:

Program:

#include <stdio.h>
#include <stdlib.h>
int main()
{
    FILE *fp1, *fp2;
    int c;
    char fname1[40], fname2[40];
    printf("##### Copy the data of one file to another #####\n");
    printf("Enter the source file : ");
    gets(fname1);
    printf("Enter the target file : ");
    gets(fname2);
    fp1 = fopen(fname1, "r");
    fp2 = fopen(fname2, "w");
    if(fp1 == NULL)
    {
        printf("Error opening file %s for reading !\n", fname1);
        exit(1);
    }
    else if(fp2 == NULL)
    {
        printf("Error opening file %s for writing ! \n", fname2);
        exit(1);
    }
    else
    {
        c = getc(fp1);
        while(c != EOF)
        {
            putc(c, fp2);
            c = getc(fp1);
        }
        fclose(fp1);
        fclose(fp2);
        printf("File copied successfully...\n");
    }
    return 0;
}
        

Output:

##### Copy the data of one file to another #####
Enter the source file : file1.txt
Enter the target file : file2.txt
File copied successfully...