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Diffstat (limited to 'gdb/doc/gdbint.texinfo')
| -rw-r--r-- | gdb/doc/gdbint.texinfo | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/gdb/doc/gdbint.texinfo b/gdb/doc/gdbint.texinfo index 5dbf7bf..bb7e5e5 100644 --- a/gdb/doc/gdbint.texinfo +++ b/gdb/doc/gdbint.texinfo @@ -5907,6 +5907,25 @@ protected with parentheses.) Declarations like @samp{struct foo *} should be used in preference to declarations like @samp{typedef struct foo @{ @dots{} @} *foo_ptr}. +Zero constant (@code{0}) is not interchangeable with a null pointer +constant (@code{NULL}) anywhere. @sc{gcc} does not give a warning for +such interchange. Specifically: + +@multitable @columnfractions .2 .5 +@item incorrect +@tab @code{if (pointervar) @{@}} +@item incorrect +@tab @code{if (!pointervar) @{@}} +@item incorrect +@tab @code{if (pointervar != 0) @{@}} +@item incorrect +@tab @code{if (pointervar == 0) @{@}} +@item correct +@tab @code{if (pointervar != NULL) @{@}} +@item correct +@tab @code{if (pointervar == NULL) @{@}} +@end multitable + @subsection Function Prototypes @cindex function prototypes |