after actual arguments are substituted, all`##'operators are deleted, and so is any whitespace next to them (including whitespace that was part of an actual argument). The result is to concatenate the syntactic tokens on either side of the`##'. ...
define call(x,y) x##y把x和y连接起来，相当于新变量xyxy+call(x,y) 就相当于xy+xy=20+20=40;参考资料：The preprocessor operator ## provides a way to concatenate actual arguments during macroexpansion. If a parameter in the replacement text is adjacent to a ##, the parameter i...
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to enclose a quote double it "A\"BC" ; or to enclose a quote escape it 'AB'+1 ; (0x00004143) string used in expression '' ; null string .word 'abcdef' ; (0x64636261) 'ef' are ignored ; warning: string value truncated 'abc'++'de' ; you can concatenate ; two strings with ...
These identifiers are not preprocessor macros. In GCC 3.3 and earlier, in C only, __FUNCTION__ and __PRETTY_FUNCTION__ were treated as string literals; they could be used to initialize char arrays, and they could be concatenated with...
strcat(): Used to concatenate two strings. strstr(): Used to find a substring in a string. memset(): Used to set the value of a block of memory to a specific value. memcpy(): Used to copy a block of memory from one location to another. The <math.h> Header File In C This head...
c2ph [pstruct] (1) - Dump C structures as generated from cc -g -S stabs c99 (1p) - compile standard C programs ca (1ssl) - sample minimal CA application cabs (3) - absolute value of a complex number cabs (3p) - return a complex absolute value ...
The definition of assert is in an #ifndef preprocessor block. If you have not defined the identifier NDEBUG through a #define directive or on the compilation command, the assert macro tests the assertion expression. If the assertion is false, the system prints a message to stderr, and raises...
As Stroustrup said "without the C preprocessor, C itself ... would have been stillborn" [23]. In fact, cpp is even used in programs written in modern languages such as Haskell [28] or λProlog. This freedom has nevertheless its price: it makes it hard to parse C source code as-is,...
Another similar example occurs if you need to concatenate strings (note that the usual C technique of putting 2 string literals next to each other is not recognized in HTML). So, for example, a macro to insert an image may look like ...