command line argument

[evantri]

I made a program to be able to change the value of four variables (will be shown in the program) at the command line arguments.

int main (int argc, char *argv[])

{

double minx = -1.0;
double maxx = 1.0;
double miny = -1.0;
double maxy = 1.0;
int i;

for (i = 1;i < argc;i++)
{
if (strcmp(argv[i],"-range") == 0)
{
minx = atof(argv[++i]);
maxx = atof(argv[++i]);
miny = atof(argv[++i]);
maxy = atof(argv[++i]);
}
}
this code will work after I compile with cc compiler. Let's say the filename is range.c

cc range.c
a.out -range 1.0 2.0 3.0 4.0

But how do I stop the program (show error message) if less than four values entered, for example

cc range.c
a.out -range 1.0 2.0 3.0

Someone help me please
thank you

[Banfa]

#include "stdlib.h"
 
...
 
if (argc < 5)
{
  // may be output an error message here
  exit(EXIT_FAILURE);
}
 

[tyreld]

#include "stdlib.h"
 
...
 
if (argc < 5)
{
  // may be output an error message here
  exit(EXIT_FAILURE);
}
 

You still have to take into account that the program name is counted as one of the arguments. So, in this example you would actually be expecting no less than 6 arguments. The first being the program name. The second being the -range option, and the remaining 4 being the values.

if (argc < 6)
{
  // error message
  exit(1);
}