Question

Right now, I have something like this…

CMD console window:
c:\users\username\Desktop> wrapfile.txt hello.txt

Hello

How would I get something like this?

CMD console window:
c:\users\username\Desktop> wrapfile.txt hello.txt hi.txt

Hello Hi

with this code?

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

int main(int argc[1], char *argv[1])
{
    FILE *fp; // declaring variable 
    fp = fopen(argv[1], "rb");
    if (fp != NULL) // checks the return value from fopen
    {
        int i;
        do
        {
            i = fgetc(fp);     // scans the file 
            printf("%c",i);
            printf(" ");
        }
        while(i!=-1);
        fclose(fp);
    }
    else
    {
        printf("Error.\n");
    }
}

Answer 1

Well, first of all: in your main declaration, you should use int main(int argc, char* argv[]) instead of what you have right now. Specifying an array size makes no sense when declaring an extern variable (that’s what argv and argc are). On the top of that, you are not using the correct types. argc is integer and argv is array of strings (which are arrays of chars). So argv is an array of arrays of chars.

Then, simply use the argc counter to loop through the argv array. argv[0] is the name of the program, and argv[1] to argv[n] will be the arguments you pass to your program while executing it.

Here is a good explanation on how this works: http://www.physics.drexel.edu/courses/Comp_Phys/General/C_basics/#command-line

My 2 cents.

---

EDIT: Here is a commented version of the working program.

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

int main(int argc, char **argv)
{
    FILE *fp;
    char c;
    if(argc < 3)    // Check that you can safely access to argv[0], argv[1] and argv[2].
    {               // If not, (i.e. if argc is 1 or 2), print usage on stderr.
        fprintf(stderr, "Usage: %s <file> <file>\n", argv[0]);
        return 1;   // Then exit.
    }

    fp = fopen(argv[1], "rb");   // Open the first file.
    if (fp == NULL)   // Check for errors.
    {
        printf("Error: cannot open file %s\n", argv[1]);
        return 1;
    }

    do   // Read it.
    {
        c = fgetc(fp); // scans the file
        if(c != -1)
            printf("%c", c);
    } while(c != -1);
    fclose(fp);   // Close it.

    fp = fopen(argv[2], "rb");   // Open the second file.
    if (fp == NULL)   // Check for errors.
    {
        printf("Error: cannot open file %s\n", argv[2]);
        return 1;
    }

    do   // Read it.
    {
        c = fgetc(fp); // scans the file
        if(c != -1)
            printf("%c", c);
    } while(c!=-1);
    fclose(fp);   // Close it.

    return 0;       // You use int main and not void main, so you MUST return a value.
}

I hope it helps.