I need to be able to input several things using the command line when I run my program in C. I would run the program using a command like the line below for example:
./programName 1 2.5 A.txt B.txt 0.0,0.5,1.0,1.5
Then I would ideally have the various entries stored in separate variables. I am having difficulty storing the last set of comma separated numbers, the 0.0,0.5,1.0,1.5 numbers, as a vector called MyVector.
Here is an example of what I have tried:
#include <stdio.h>
#include <stdlib.h>
int main (int argc, char *argv[]){
int x = atoi(argv[1]); // x = 1
float y = atof(argv[2]); // y = 2.5
char *AFileName = argv[3]; // AFileName = A.txt
char *BFileName = argv[4]; // BFileName = B.txt
double MyVector[4] = atof(argv[5]); // MyVector = [0.0,0.5,1.0,1.5]
printf("x = %d\n",x);
printf("y= %f\n",y);
printf("AFileName= %s\n",HFileName);
printf("BFileName= %s\n",AFileName);
for(int i=0;i<4;i++)
{
printf("MyVector[%d] = %f\n",i,MyVector[i]);
}
}
All of these work except for the line where I try and store the values in MyVector.
This
double MyVector[4] = atof(argv[5]); // MyVector = [0.0,0.5,1.0,1.5]
won't work as you wanted.
0.0,0.5,1.0,1.5
is a single string. So, you need to tokenzing it and retrieve each element and then do the conversion using atof()
.
You can use strtok()
to tokenize for example.
double MyVector[4];
char *p = strtok(argv[5], ",");
size_t i = 0;
while(p && i<4) {
MyVector[i++] = atof(p);
p = strtok(NULL, ",");
}
If you are going to use strtok()
be aware of its pitfalls. It modifies its input string. See strtok()
for details.