Article: Q22321
Product(s): Microsoft C Compiler
Version(s): 1.0,1.5,2.0,4.0,5.0,6.0
Operating System(s):
Keyword(s): kbLangC kbVC100 kbVC150 kbVC200 kbVC400 kbVC500 kbVC600
Last Modified: 29-NOV-2001
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The information in this article applies to:
- Microsoft C for MS-DOS
- Microsoft C/C++ for MS-DOS
- Microsoft Visual C++, versions 1.0, 1.5, 2.0, 4.0
- Microsoft Visual C++, 32-bit Enterprise Edition, versions 5.0, 6.0
- Microsoft Visual C++, 32-bit Professional Edition, versions 5.0, 6.0
- Microsoft Visual C++, 32-bit Learning Edition, version 6.0
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SUMMARY
=======
The text below lists some of the most common errors that occur programming in
the C language. Any one of these items can cause unpredictable results, such as
invalid data. Some are caught by the compiler and reported as errors or
warnings.
- Using an automatic variable that has not been initialized
- Omitting a closing comment delimiter
- Using an array index greater than the length of the array (In C, array
indexes run from zero to <length>-1.)
- Omitting a semicolon or a closing brace
- Using an uninitialized pointer
- Using a forward slash when a backslash is required (for example, substituting
"/n" for "\n.")
- Using "=" in a comparison where "==" is desired
- Overwriting the null terminator for a string
- Prematurely terminating a function declaration with a semicolon (The compiler
often flags the "orphan" block of code as a syntax error.)
- Specifying the values of variables in a scanf() statement instead of their
addresses
- Failing to declare the return type for a function
- Assuming an expression evaluation order when using an expression with side
effects (For example, a[i] = i++; is ambiguous and dangerous.)
- Failing to account that a static variable in a function is initialized only
once
- Omitting a "break" from a case in a switch statement (Execution "falls
through" to subsequent cases.)
- Using "break" to exit a block of code associated with an if statement (The
break statement exits a block of code associated with a for, switch, or while
statement.)
- Comparing a "char" variable against EOF (-1). The following idiom results in
an infinite loop when char is unsigned. Note that char is signed by default,
so the following will only fail when using the "/J" compiler option:
char c;
while ((c = getchar()) != EOF)
{
}
Additional query words:
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Keywords : kbLangC kbVC100 kbVC150 kbVC200 kbVC400 kbVC500 kbVC600
Technology : kbVCsearch kbVC400 kbAudDeveloper kbZNotKeyword8 kbvc150 kbvc100 kbCCompSearch kbZNotKeyword3 kbVC500 kbVC600 kbVC200 kbVC32bitSearch kbVC500Search
Version : :1.0,1.5,2.0,4.0,5.0,6.0
Issue type : kbinfo
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