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Named parameters: Difference between revisions
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}</lang>
=={{header|C}}==
C has no direct support for named parameters to functions, but it does permit named parameters to struct initializers. These can be used to simulate named function parameters:
{{works with|C99}}
<lang c>#include <stdio.h>
// 1. Named parameters
typedef struct { int x, y, z; } FTest_args;
void FTest (FTest_args args) {
printf("x: %d, y: %d, z: %d\n", args.x, args.y, args.z);
}
#define FT(...) FTest((FTest_args){ __VA_ARGS__ })
// 2. Default parameters
#define DFT(...) FTest((FTest_args){ .x = 142, .y = 143, .z = 144, __VA_ARGS__ })
// 3. Convenience wrapper to avoid accessing args as "args.name"
void FTest2 (int x, int y, int z) {
printf("x: %d, y: %d, z: %d\n", x, y, z);
}
static inline void FTest2_default_wrapper (FTest_args args) {
return FTest2(args.x, args.y, args.z);
}
#define DF2(...) FTest2_default_wrapper((FTest_args){ .x = 142, .y = 143, .z = 144, __VA_ARGS__ })
int main(int argc, char **argv)
{
// Named parameters
FTest((FTest_args){ .y = 10 });
FTest((FTest_args){ .y = 10, .z = 42 });
FT( .z = 47, .y = 10, .x = 42 );
// Default parameters
DFT();
DFT( .z = 99 );
// Default parameters with wrapper
DF2();
DF2( .z = 99 );
return 0;
}</lang>
As a bonus, default values for the parameters left unspecified can be either implicitly set to zero by the struct initializer, or supplied in a wrapper-macro definition. But this is not idiomatic C by any stretch.
=={{header|C++}}==
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