You have to make two calls to the getch()function when you read extended characters

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Article ID: 57888 - View products that this article applies to.
This article was previously published under Q57888
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SUMMARY

In Microsoft C, when reading extended characters you must make two calls to getch() because the first call returns a value indicating that the key is an extended character. The second call returns the actual key code. When you are reading an extended character, the first return value will be either 0xE0 or 0x00, depending on which extended key is pressed.

Sample Code

#include <stdio.h>
#include <conio.h>

void main(void)
{
    int ch, scan;

    do {
        ch = getch();    /* 1st getch() gets ASCII code */ 
        printf("Character is %d\n", ch);
           if (ch == 0x00 || ch == 0XE0)  { /* if extended key */ 
            scan = getch();  /* 2nd getch() gets "scan code" */ 
            printf("\tExtended character:  scan is %d\n", scan);
        }
    }  while (ch != 27);    /* exit loop on ESC */ 
}
For a discussion of keystrokes and scan codes, refer to "The New Peter Norton Programmer's Guide to the IBM PC & PS/2," by Peter Norton and Richard Wilton.

Properties

Article ID: 57888 - Last Review: April 28, 2005 - Revision: 4.0
APPLIES TO
  • The C Run-Time (CRT), when used with:
    • Microsoft Visual C++ 1.0 Professional Edition
    • Microsoft Visual C++ 1.5 Professional Edition
    • Microsoft Visual C++ 1.0 Professional Edition
    • Microsoft Visual C++ 2.0 Professional Edition
    • Microsoft Visual C++ 2.1
    • Microsoft Visual C++ 4.0 Standard Edition
    • Microsoft Visual C++ 5.0 Standard Edition
    • Microsoft Visual C++ 6.0 Service Pack 5
Keywords: 
kbcode kbinfo KB57888
Retired KB Content Disclaimer
This article was written about products for which Microsoft no longer offers support. Therefore, this article is offered "as is" and will no longer be updated.

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