/w

Disables all compiler warnings.

/W n

Specifies the highest level of warning generated by the compiler. Valid warning levels for n range from 0 to 4:

• Level 0 disables all warnings.

• Level 1 displays severe warnings. Level 1 is the default warning level at the command line.

• Level 2 displays all level 1 warnings and warnings less severe than level 1.

• Level 3 displays all level 2 warnings and all other warnings recommended for production purposes.

• Level 4 displays all level 3 warnings plus informational warnings, which in most cases can be safely ignored. This option should be used only to provide "lint" level warnings and is not recommended as your usual warning level setting.

For a new project, it may be best to use /W4 in all compilations. This will ensure the fewest possible hard-to-find code defects.

/Wall

Enables all warnings, including those disabled by default. See .

/WX

Treats all compiler warnings as errors. For a new project, it may be best to use /WX in all compilations; resolving all warnings will ensure the fewest possible hard-to-find code defects.

The linker also has a /WX option; see  for more information.

/w ln

Specifies the level for a particular warning. The first parameter sets the warning level (same as /Wn) and the second parameter is the actual warning number.

For example, /w14326 causes C4326 to be generated as a level 1 warning.

/wd n

Disables the specified compiler warning where nis the compiler warning number.

For example, /wd4326 disables compiler warning C4326.

/we n

Treats the specific compiler warning as an error where n is a compiler warning.

For example, /we4326 flags warning number C4326 as an error.

/wo n

Reports the error only once where n is a compiler warning.

For example, /wo4326 will cause warning C4326 to be reported only once.