How to use C++ streams with a c_str() library API.

Question

Hi here is my code snippet:

RIT128x96x4StringDraw(HWREGBITW(&g_ulFlags, 0) ? "1" : "0", 48, 32, 15);

This is only used to print some string on the screen. I want a function or means to print numericals which can be increamented , like we do in c++

for(;;)
{ 
    cout<<i++;
}

Answer 1

From your other question Arm Cortex Display, we see the prototype of the function.

void RIT128x96x4StringDraw(char *str, ulong x, ulong y, unsigned char level);

Here are the parameters,

• x and y are locations on the screen. They are character locations, so this function draws text like a printf() or cout.
• The level parameter is an intensity; I guess you have a gray scale LCD and this is how white or black the text is.
• str is a C string that you wish to print.

Here is a sample that will print a number in a traditional C mode.

#include <stdio.h>
#include <stdlib.h>
void print_number(int i)
{
    char buffer[36];
    itoa (i,buffer,10);
    RIT128x96x4StringDraw(&buffer[0], 0, 0, 15);
}

This uses the itoa() function to convert a number to a C String. If you prefer C++ syntax, the following code may be more preferable,

void print_number(int i)
{
  std::ostringstream oss;
  oss << i++;
  /* What ever else you wish to do... */
  RIT128x96x4StringDraw(oss.str().c_str(), 0, 0, 15);
}

This code is not meant to be bullet proof production code and may not even compile. It is to demonstrate a concept.

Here is an implementation of itoa() if your target is resource constrained.