例7-18.prg

几个VFP程序实例

clear
store 100 to x1,x2
set udfparms to value
do p4 with x1,(x2)  && x1按引用传递，(x2)按值传递
? "第一次：",x1,x2
store 100 to x1,x2
p4(x1,(x2))         &&x1、x2都按值传递
? "第二次：",x1,x2
set udfparms to reference
do p4 with x1,(x2)    && x1按引用传递，(x2)按值传递
? "第三次：",x1,x2
store 100 to x1,x2
p4(x1,(x2))           && x1按引用传递，(x2)按值传递
? "第四次：",x1,x2
* 过程p4
procedure p4
parameters x1,x2
store x1+1 to x1
store x2+1 to x2
endproc