EECS 2031 Page 1 of 2
LAB 6 ─ Command-Line Arguments
1. Specification
Write a C program to implement a simple calculator that accepts input in the following format and
displays the result of the computation:
calc [operand_1] [operator] [operand_2]
The operands operand_1 and operand_2 are non-negative integers. The operator is one of the
following: addition (+), subtraction (-), multiplication (x), division (/) and modulo (%).
Note: For the multiplication operator, use letter ‘x’. If you use the asterisk ‘*’, your program will not
work properly.
2. Implementation
• The program to be submitted is named calc.c. Use the given template calc.c and fill in your
code. Complete functions main()in file calc.c.
• Note that the command-line arguments are all strings. Therefore you need to implement a function
to convert a string to an integer to obtain operand_1 and operand_2.
• Sometimes users may forget the command syntax and they may type only the command “calc”. In
that case, display the following reminder message:
Usage: calc [operand_1] [operator] [operand_2]
• Other than that, assume that all inputs are valid. No error checking is required on inputs.
• You may define your own variables inside functions main(). Do not use global variables (defined
outside functions main()).
• You may define and implement your own function(s) inside file calc.c if needed.
• Do not use any C library functions (e.g., atoi).
• To compile the program, use the following command: gcc –o calc calc.c
• There must be at least a white space between an operand and the operator. That is how the
command-line arguments are separated.
3. Sample Inputs/Outputs
See file calc_io.txt for sample inputs and outputs.
EECS 2031 Page 2 of 2
Common Notes
• Complete the headers in the files to be submitted with your student and contact information.
• Assume that all inputs are valid. No error checking is required on inputs.
• You may use either pointers or array indexing or both.
