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The C–Pascal Interface 91

Precautions with Compatible Types

This section describes the precautions you should take when working with

compatible types.

Theshortreal Type

The Pascal shortreal and C float compatibility works if you pass by

reference. See “Value Parameters” on page 112 for examples that show you

how to pass by value.

Character Strings

C has several assumptions about strings. All C strings are:

• Passed by reference since C strings are arrays

• Terminated by a null byte

• Located in static variable storage

You can satisfy these assumptions as follows:

• Pass by reference by making the strings var, in, out, or in out

parameters.

• Provide the null byte explicitly before passing a string to C. Pascal

guarantees the null byte only if the string is a constant. The null byte is not

required by the ISO Pascal Standard.

array array - Same as element type

variant record struct/union --

ﬁelds in packed

record

bit ﬁeld - -

Table 6-2 C and Pascal Size and Alignment of Compatible Types with –xl

Pascal Type C Type Size (bytes) Alignment (bytes)

real float 44

integer short int 22

Table 6-1 C and Pascal Size and Alignment of Compatible Types (Continued)

Pascal Type C Type Size (bytes) Alignment (bytes)

1 2 ... 110 111 112 113 114 115 116 117 118 119 120 ... 332 333

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