valueAndReference
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Passing Parameters By Value And Reference

TCL has no types, everything is a string. SAAPHIRE is a C language API, so all parameters to the API's functions have types. Any C type whose value can be naturally represented by a string can be passed to SoftWish SAA procedures by value. For example, suppose there were some SAAPHIRE C function:

SAA_dummyByValueFunction (

int a,

float b,

char c)

Then we could call this from SoftWish like this:

SAA_DummyByValueFunction 22 34.7 C

TCL and hence SoftWish, has no pointers. One passes a value by reference by passing the name of the variable containing that value. A C function like:

SAA_dummyByReferenceFunction (

const int *a,

const float *b,

char *c)

would be called from SoftWish like this:

set a 22

set b 34.7

set c C

SAA_dummyByReferenceFunction a b c

Note that we can now also call:

SAA_DummyByValueFunction $a $b $c

with the same effect as our previous call to this function.

There is no C data type for multi-character strings, so they must be passed by reference, like this:

set c manyCharacters

SAA_dummyByReferenceFunction a b c

There is no difference between the string representing a short, an integer and a long value nor is there a difference between the string representing a double and a float value. Consequently SoftWish does not distinguish between shorts, ints and longs, nor does it distinguish floats from doubles.

See Also

Arrays Structures

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