send PHP string to C++ - php

Question

I am trying to pass over from php a string into C++, i managed to figure out how to pass numbers, but it doesn't work for letters. Here's what i have that works for PHP
<?php
$r = 5;
$s = 12;
$x= 3;
$y= 4;
$q= "Hello World";
$c_output=`project1.exe $r $s $x $y $q`; // pass in the value to the c++ prog
echo "<pre>$c_output</pre>"; //received the sum
//modify the value in php and output
echo "output from C++ programm is" . ($c_output + 1);
?>
This sends the variables r,s,x,y, and q to the C++ programm project1.exe and IT WORKS, but the problem is that it doesn't work for the string variable $q.
Here's the code that I have in my C++ programm, it's simple:
#include<iostream>
#include<cstdlib>
#include<string>
using namespace std;
int main(int in, char* argv[]) {
int val[2];
for(int i = 1; i < in; i++) { // retrieve the value from php
val[i-1] = atoi(argv[i]);
}
double r = val[0];
double s = val[1];
double x = val[2];
double y = val[3];
double q = val[4]; // here's the problem, as soon as i try to define val[4] as a string or char, it screws up
cout << r;
cout <<s;
cout << x;
cout << y;
cout << q;
// will output to php
return 0;
}
It works, but for the string "Hello world" which i pass through $q from PHP doesn't give me the string back (i know it's defined as a double, but as soon as i try to change it to a string or a char variable the code just doesn't compile).
Please explain to me how i have to go around this problem so that $q can be processed as a string. FYI, I am a newbie to programming (6 months in).

Answer 1

Try not converting the final argument using atoi(argv[i]). Just keep it as argv[i].
for(int i = 1; i < in-1; i++)
{
val[i-1] = atoi(argv[i]);
}
q = argv[i];

Answer 2

It doesn't work for letters because you are doing atoi(..)(which converts char-string to integer) in the C++ program.
Have some means of letting the program know what to expect -- whether a number or a string. May be the first argument can help the program differentiate, like may be the following:
$c_output = `project1.exe nnsnns 1 2 string1 3 4 string2`
Then you could do:
for(int i = 0/*NOTE*/,len=strlen(argv[1]); i < len; i++) { // retrieve the value from php
if (argv[1][i] == 'n'){
//argv[2+i] must be an integer
}else if (argv[1][i] == 's'){
//argv[2+i] is a string
}
}
Of course you should check if (strlen(argv[1]) == in-2).
BTW, in the C++ code above, val is a array holding 2 ints; and you are trying to access much beyond index 1.
To pass one single string to the C++ you would do something like the following:
$output = `project1.exe $q`; //Read below.
NOTE: $q must be a single word. No spaces, no extra characters like '|', '&', or any other character which the shell might interpret differently. $q must be clean before you pass that on to C++ Program. If $q is more than one word, use quotes.
C++ Part (Just try the following, then you can modify as you go along)
cout<<argv[1]<<endl;