Get the output of one C program into a variable in another C program

Question

I have 2 C programs. Say one is program-1.c

int main(){
printf("hello world");
}

Now in 2nd code named program-2.c, I want the output of 1st code into a variable, so that I can have the output "hello world" into a variable in the 2nd C code.

How can I do this?

Answer 1

You can use the popen function for this:

FILE* proc1 = popen("./program1", "r");
// Usual error handling code goes here
// use the usual FILE* read functions
pclose(proc1);

Answer 2

You will need to run the two programs in two separate processes and then use some sort of IPC mechanism to exchange data between the two processes.

Answer 3

On many operating systems you can get the output from one console program as input to the next, perhaps

program-1 > program-2

you can then read the result from standard input

std::string  variable;

std::getline(std::cin, variable);