Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
Command line arguments in C/C++
It is possible to pass some values from the command line to your C programs when they are executed. These values are called command line arguments and many times they are important for your program especially when you want to control your program from outside instead of hard coding those values inside the code.
The command line arguments are handled using main() function arguments where argc refers to the number of arguments passed, and argv[] is a pointer array which points to each argument passed to the program. Following is a simple example which checks if there is any argument supplied from the command line and take action accordingly −
Example
#include <stdio.h>
int main( int argc, char *argv[] ) {
if( argc == 2 ) {
printf("The argument supplied is %s\n", argv[1]);
}
else if( argc > 2 ) {
printf("Too many arguments supplied.\n");
}
else {
printf("One argument expected.\n");
}
}Output
$./a.out testing The argument supplied is testing
Output
$./a.out testing1 testing2 Too many arguments supplied.
Output
$./a.out One argument expected
It should be noted that argv[0] holds the name of the program itself and argv[1] is a pointer to the first command line argument supplied, and *argv[n] is the last argument. If no arguments are supplied, argc will be one, and if you pass one argument then argc is set at 2.
You pass all the command line arguments separated by a space, but if argument itself has a space then you can pass such arguments by putting them inside double quotes "" or single quotes ''. Let us re-write above example once again where we will print program name and we also pass a command line argument by putting inside double quotes −
Example
#include <stdio.h>
int main( int argc, char *argv[] ) {
printf("Program name %s\n", argv[0]);
if( argc == 2 ) {
printf("The argument supplied is %s\n", argv[1]);
}
else if( argc > 2 ) {
printf("Too many arguments supplied.\n");
}
else {
printf("One argument expected.\n");
}
}Output
$./a.out "testing1 testing2" Progranm name ./a.out The argument supplied is testing1 testing2
4K+ Views
