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/W, /w   (Warning Level)

OverviewHow Do ICompiler Options

These options control the number of warning messages produced by the compiler. They affect only source files, not object (.OBJ) files.

Command Line Project Settings Description
/W0 or /w None Turns off all warning messages.
/W1 Level 1 Displays severe warning messages. This is the default.
/W2 Level 2 Displays a less-severe level of warning message than /W1.
/W3 Level 3 Displays less-severe warnings than /W2, such as warnings about function calls that precede their function prototypes. /W3 is the most sensitive warning level recommended for production pruposes.
/W4 Level 4 Displays informational warnings which in most cases can be safely ignored. /W4 should be used occasionally to provide “lint” level warnings and is not recommended as your usual warning level setting.
/WX Warnings As Errors Treats all warnings as errors. If there are any warning messages, an error message is emitted and compilation continues.

To find this option in the development environment, click Settings on the Project menu. Then click the C/C++ tab, and click General in the Category box.

You can also use #pragma warning() to control the level of warning reported at compile time.

On the command line, a space between /W and 0, 1, 2, 3, 4, or X is optional.

The Build Errors documentation describes the warnings, indicates each warning’s level, and indicates potential problems (rather than actual coding errors) with statements that may not compile as you intend.