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Declaring a function that uses array parameter variables

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• Syntax used to declare functions
  • Recall the syntax to declare a function: (See: click here)

    [extern] returnType functionName ( param1type, param2type, .... )

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• Declaring a function that has an array parameter variable
  • Just follow the standard syntax

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  • To specify a one-dimensional array as parameter variable, use (the "convenient notattion"):

    datatype [ ]

    Example:

    [extern] double sum( double [ ] );

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  • To specify a two-dimensional array as parameter variable, use:

    datatype [ ] [ SIZE2 ]

    Example:

    [extern] double sum( double [ ] [10] );

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  • Example:

    /* -------------------------------------------- Declare a function with an array parameter -------------------------------------------- */ extern void func( double [ ] ); int main( int argc, char* argv[] ) { double a[10]; int i; for ( i = 0; i < 10; i++ ) a[i] = i; func( a ); } void func( double x[ ] ) { int i; for ( i = 0; i < 10; i++ ) printf( "x[%d] = %lf\n", i, x[i] ); }

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  • Example Program: (Demo above code)                                                
    • Prog file: click here

    How to run the program:

    Right click on link(s) and save in a scratch directory To compile:   gcc array-param4.c To run:          ./a.out

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• Postscript
  • You can really make the function declaration look more normal with a variable name that is treated as comment:

    /* -------------------------------------------- Declare a function with an array parameter -------------------------------------------- */ extern void func( double x[ ] ); // add a dummy var name !!! int main( int argc, char* argv[] ) { double a[10]; int i; for ( i = 0; i < 10; i++ ) a[i] = i; func( a ); } void func( double x[ ] ) { int i; for ( i = 0; i < 10; i++ ) printf( "x[%d] = %lf\n", i, x[i] ); }