C program to find the sum of N integer numbers using command line arguments

Learn: How to find the sum of N integer numbers using command line arguments? Here, values will be given through the command line.

As we have discussed in command line argument tutorial, that we can also give the input to the program through the command line.

First visit this program: Find sum of two integer numbers using command line arguments in C.

In this program, we are going to find the sum of N integer numbers and numbers will be provided through the command line, we can pass any number of integer values (in this example, we are providing 6 integer numbers) and program will find and print the sum of all input numbers.

Sample input

`./main  10  20 30 40 50 60`

Here, ./main is the program's executable file name, 10 20 30 40 50 and 60 are the input values.

Sample output

```arg[ 1]: 10
arg[ 2]: 20
arg[ 3]: 30
arg[ 4]: 40
arg[ 5]: 50
arg[ 6]: 60
SUM of all values: 210```

Program to find the sum of N integer numbers using command line arguments in C

```#include <stdio.h>

int main(int argc, char *argv[])
{
int a,b,sum;
int i; //for loop counter

if(argc<2)
{
printf("please use \"prg_name value1 value2 ... \"\n");
return -1;
}

sum=0;
for(i=1; i<argc; i++)
{
printf("arg[%2d]: %d\n",i,atoi(argv[i]));
sum += atoi(argv[i]);
}

printf("SUM of all values: %d\n",sum);

return 0;
}
```

Output

```./main 10 20 30 40 50 60
arg[ 1]: 10
arg[ 2]: 20
arg[ 3]: 30
arg[ 4]: 40
arg[ 5]: 50
arg[ 6]: 60
SUM of all values: 210
```

What is atoi()?

atoi() is a library function that converts string to integer, when program gets the input from command line, string values transfer in the program, we have to convert them to integers (in this program). atoi() is used to return the integer of the string arguments.