Microsoft KB Archive/62663

= PRB: CodeView May Appear to Hang on gets If Screen Swap Is Off =

Article ID: 62663

Article Last Modified on 10/23/2003

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APPLIES TO


 * Microsoft CodeView 3.0
 * Microsoft CodeView 3.0
 * Microsoft CodeView 3.0
 * Microsoft CodeView 4.0
 * Microsoft CodeView 4.01
 * Microsoft CodeView 4.01
 * Microsoft CodeView 4.1
 * Microsoft CodeView 3.0
 * Microsoft CodeView 4.1
 * Microsoft CodeView 4.1
 * Microsoft CodeView 4.1

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This article was previously published under Q62663



SYMPTOMS
The Microsoft CodeView Debugger will appear to hang when you step or execute past a call to the gets run-time routine if the Screen Swap option is turned off.



CAUSE
The apparent lock-up results because the gets call causes focus to shift to the debuggee's screen and there is no way for CodeView to get to that screen with Screen Swap off.

Since in MS-DOS, the debuggee's screen still displays CodeView, you may be able to type in the information and press Return to continue. This will temporarily display the debuggee's input over CodeView's screen. A better method in MS-DOS is to break execution with CTRL+C so that you may turn swapping back on.



RESOLUTION
To get past this deadlock with CVP under OS/2, manually switch screen groups to the one labeled &quot;CVP app appname.EXE&quot;. Once there, you can provide a response to the waiting gets call. After entering a string, you can switch back to the screen group running CVP and continue debugging.



MORE INFORMATION
The sample code below illustrates this situation. Compile the code as indicated and bring up the .EXE in CodeView. Select the Option menu and turn off Screen Swap if it is on. Next, step past the gets call. In MS-DOS, you will need to press CTRL+C to regain control. In OS/2, you will need to switch screen groups to provide the necessary input to the program.

Sample Code
/* Compile options needed: /Zi /Od


 * 1) include 

char string[256];

void main (void) {   printf ( &quot;Enter a string: &quot;) ; gets ( string ) ; printf ( &quot;Echoing : %s\n&quot;, string) ; }

Additional query words: 3.00 3.50 4.00 4.10

Keywords: kb16bitonly KB62663

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