c programming reading multiple files technique - c

Question

I am curious what is the best way to open multiple files. I know you use a combination of FILE *inputfp1; and inputfp1 = fopen(argv[1], "r"); then check for errors. I would like to know the best way to do this.
Is it best to open and close one file at a time like this?
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
int main(int argc, char **argv) {
char line[80] = {0};
FILE *inputfp1;
//input = fopen("myfile.txt", "r");
inputfp1 = fopen(argv[1], "r"); //Open file for read.
if (inputfp1 == NULL)
{
printf("Error opening file %s!",argv[1]); //Program prints error message and closes if file is not found
exit(0);
}
if( argc == 7 )
{
/*printf("The first argument supplied is %s\n", argv[1]);
printf("The second argument supplied is %s\n", argv[2]);
printf("The third argument supplied is %s\n", argv[3]);
printf("The first argument supplied is %s\n", argv[4]);
printf("The second argument supplied is %s\n", argv[5]);
printf("The third argument supplied is %s\n", argv[6]);
printf("The third argument supplied is %s\n", argv[7]);*/
}
else if( argc > 7 )
{
printf("Too many arguments supplied.\n");
exit( 1 );
}
else
{
printf("Not enough arguments supplied. \n");
exit( 1 );
}
//Unique behavior on file1
while(fgets(line, 80, inputfp1) != NULL)
{
//do work on file1
}
fclose(inputfp1);
inputfp1 = fopen(argv[2], "r"); //Open file for read.
if (inputfp1 == NULL)
{
printf("Error opening file %s!",argv[1]); //Program prints error message and closes if file is not found
exit(0);
}
//Unique behavior on file2
while(fgets(line, 80, inputfp1) != NULL)
{
//do work on file2
}
fclose(inputfp1);
return 0;
}
Is it better to create all the file pointers and open all the files at once like this?
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
int main(int argc, char **argv) {
char line[80] = {0};
FILE *inputfp1;
FILE *inputfp2;
FILE *inputfp3;
FILE *inputfp4;
FILE *inputfp5;
FILE *inputfp6;
//input = fopen("myfile.txt", "r");
inputfp1 = fopen(argv[1], "r"); //Open file for read.
inputfp2 = fopen(argv[2], "r"); //Open file for read.
inputfp3 = fopen(argv[3], "r"); //Open file for read.
inputfp4 = fopen(argv[4], "r"); //Open file for read.
inputfp5 = fopen(argv[5], "r"); //Open file for read.
inputfp6 = fopen(argv[6], "r"); //Open file for read.
if (inputfp1 == NULL)
{
printf("Error opening file %s!",argv[1]); //Program prints error message and closes if file is not found
exit(0);
}
//The rest of error checking.
if( argc == 7 )
{
/*printf("The first argument supplied is %s\n", argv[1]);
printf("The second argument supplied is %s\n", argv[2]);
printf("The third argument supplied is %s\n", argv[3]);
printf("The first argument supplied is %s\n", argv[4]);
printf("The second argument supplied is %s\n", argv[5]);
printf("The third argument supplied is %s\n", argv[6]);
printf("The third argument supplied is %s\n", argv[7]);*/
}
else if( argc > 7 )
{
printf("Too many arguments supplied.\n");
exit( 1 );
}
else
{
printf("Not enough arguments supplied. \n");
exit( 1 );
}
//Unique behavior on file1
while(fgets(line, 80, inputfp1) != NULL)
{
//do work on file1
}
fclose(inputfp1);
//Unique behavior on file2
while(fgets(line, 80, inputfp2) != NULL)
{
//do work on file2
}
fclose(inputfp2);
//The rest of reading and closing files.
return 0;
}
Are there any better ways I missed?

Answer 1

A good way of doing this would be putting all your file pointers in an array:
FILE *inputfp[6];
for(int i=0;i<6;i++)
{
inputfp[i] = fopen(argv[i+1], "r"); //Open file for read.
if (inputfp[i] == NULL)
{
printf("Error opening file %s!",argv[i+1]); //Program prints error message and closes if file is not found
exit(0);
}
}

Answer 2

I'd do it the first way, but use a loop:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
int main(int argc, char **argv) {
char line[80] = {0};
FILE *inputfp1;
if( argc == 7 )
{
/*printf("The first argument supplied is %s\n", argv[1]);
printf("The second argument supplied is %s\n", argv[2]);
printf("The third argument supplied is %s\n", argv[3]);
printf("The first argument supplied is %s\n", argv[4]);
printf("The second argument supplied is %s\n", argv[5]);
printf("The third argument supplied is %s\n", argv[6]);
printf("The third argument supplied is %s\n", argv[7]);*/
}
else if( argc > 7 )
{
printf("Too many arguments supplied.\n");
exit( 1 );
}
else
{
printf("Not enough arguments supplied. \n");
exit( 1 );
}
for (int i = 1; i < argc; ++i)
{
inputfp1 = fopen(argv[i], "r"); //Open file for read.
if (inputfp1 == NULL)
{
printf("Error opening file %s!",argv[i]); //Program prints error message and closes if file is not found
exit(0);
}
while(fgets(line, 80, inputfp1) != NULL)
{
//do work
}
fclose(inputfp1);
}
return 0;
}