Question

Consider this code:

#include <iostream>

int main() 
{
   int iTemp = 0;

   iTemp += 1;     // Valid

   iTemp + = 1;   // This gives an error ( note the space between '+' and '=')

   return 0;
}

Should the parser not automatically have consumed this space and checked for the presence of ‘=’ as ‘+=’ is also a valid token, rather than throwing an error ?

Similarly I get an error for doing < iostream >

Can someone please explain.

Answer 1

Doesn’t work.
The first step of C compilation is tokenization – breaking the sequence of characters to separate language elements. For example:
int x=333; becomes the list int, x, =, 333 and ;‘.
Once this is done, the compiler can figure out which token means what and how to combine them.

If tokenization sees the sequence +=, it generates one token. If it sees a space, it generates two: + and =.