please forgive me if this is a noob question, but i'm a beginner at C, learning only for a while. I tried to write a program that sums up two numbers (provided as params to the application). The code is like this:
#include <stdlib.h> #include <stdio.h> int main( int argc, char** argv) { int a = atoi(argv[0]); int b = atoi(argv[1]); int sum = a+b; printf("%d", sum); return 0; } But I get incorrect results - huge numbers even for small inputs like 5 and 10. What is wrong here?
The first argument to the program is the name of the program itself. Try using the following instead.
int a = atoi(argv[1]); int b = atoi(argv[2]); 
atoi(argv[0]) be 0 in pretty much all cases?
Thats because argv[0] is the name of your executable.
You should use argv[1] and argv[2].
And make sure the count (argc)is 3.
You'll want to use argv[1] and argv[2].
The first element in argv (argv[0]) is the command itself. This will be your program executable name...
Assuming the name of your program is noob.c and you compile it with gcc ./noob.c -o noob. You have to make these changes.
int a = atoi(argv[1]); int b = atoi(argv[2]); You have to run it ./noob 1 2 and voila the output will be 3.
argc is 3 viz number of command line arguments, your input will be the 1st and 2nd values from the command line.
That's because argv[0] is the program name, not the first argument (i.e. if you run myapp 4 5, argv becomes myapp, 4, 5).
printf("argv[0] = %s\n", argv[0]); printf("argv[1] = %s\n", argv[1]);followed byprintf("a = %d\nb = %d\n", a, b);after the calls toatoi(). Had you done that, you probably wouldn't have needed to ask the question. (Don't forget to print a newline after the answer!).#include <cstdlib>is a C++ header. Use#include <stdlib.h>.