C Program to Merge Contents of Two Files into a Third File

This C Program join lines of two given files and store them in a new file.

Here is source code of the C Program to join lines of two given files and store them in a new file. The C program is successfully compiled and run on a Linux system. The program output is also shown below.

```
/*
```

 * C Program to Join Lines of Two given Files and

```
 * Store them in a New file
```
```
 */
```
```
#include <stdio.h>
```
```
#include <stdlib.h>
```
```
 
```
```
/* Function Prototype */
```
```
int joinfiles(FILE *, FILE *, FILE *);
```
```
 
```
```
char ch;
```
```
int flag;
```
```
 
```
```
void main(int argc, char *argv[])
```
```
{
```
```
    FILE *file1, *file2, *target;
```
```
 
```
```
    file1 = fopen(argv[1], "r");
```
```
    if (file1 == NULL)
```
```
    {
```
```
        perror("Error Occured!");
```
```
    }
```
```
    file2 = fopen(argv[2], "r");
```
```
    if (file2 == NULL)
```
```
    {
```
```
        perror("Error Occured!");
```
```
    }
```
```
    target = fopen(argv[3], "a");
```
```
    if (target == NULL)
```
```
    {
```
```
        perror("Error Occured!");
```
```
    }
```
```
 
```

    joinfiles(file1, file2, target);        /* Calling Function */

```
 
```
```
    if (flag == 1)
```
```
    {
```

        printf("The files have been successfully concatenated\n");

```
    }
```
```
}
```
```
 
```

/* Code join the two given files line by line into a new file */

```
 
```

int joinfiles(FILE *file1, FILE *file2, FILE *target)

```
{
```

    while ((fgetc(file1) != EOF) || (fgetc(file2) != EOF))

```
    {
```
```
        fseek(file1, -1, 1);
```

        while ((ch = fgetc(file1)) != '\n')

```
        {
```
```
            if (ch == EOF)
```
```
            {
```
```
                break;
```
```
            }
```
```
            else
```
```
            {
```
```
                fputc(ch, target);
```
```
            }
```
```
        }
```

        while ((ch = fgetc(file2)) != '\n')

```
        {
```
```
            if (ch == EOF)
```
```
            {
```
```
                break;
```
```
            }
```
```
            else
```
```
            {
```
```
                fputc(ch, target);
```
```
            }
```
```
        }
```
```
        fputc('\n', target);
```
```
    }
```
```
    fclose(file1);
```
```
    fclose(file2);
```
```
    fclose(target);
```
```
    return flag = 1;
```
```
}
```

$ cc file7.c
$ ./a.out lines.c words.c final.c
The files have been successfully concatenated
 
/* FIRST FILE */
 
/*
Hello!!
This is a C Program File.
Consider a code to Add two numbers 
*/
 
#include <stdio.h>
/* Function Prototype */
int sum(int,  int);
void main()
{
    int num1, num2;
    printf("Enter Number1 and Number2:");
    scanf("%d %d ", num1, num2);
    sum(num1, num2);
}
 
int sum(int a, int b)
{
    return a + b;
}
 
/* SECOND FILE */
 
/*
 * this is temporary file for use in file handling
 */
#include <stdio.h>
 
int sqrt(int);
void main()
{
    int num;
    printf("enter the number:");
    scanf("%d", &num);
    sqrt(num);
    printf("The square of the given number is:", num);
}
int sqrt(int num)
{
    return num*num;
}
 
/* CONCATENATED FILE */
/*
Hello!! * this is temporary file for use in file handling
This is a C Program File. *
Consider a code to Add two numbers  */
*/
#include <stdio.h>
#include <stdio.h>
int sqrt(int);
/* Function Prototype */void main()
{
int sum(int,  int);    int num;
void main()    printf("enter the number:");
{    scanf("%d", &num);
    int num1, num2;    sqrt(num);
    printf("Enter Number1 and Number2:");    printf("The square of the given number is:", num);
    scanf("%d %d ", num1, num2);}
    sum(num1, num2);int sqrt(int num)
}{
    return num*num;
int sum(int a, int b)}
{
    return a + b;
}

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