Section 9: Branching and Looping 129

Keystrokes

Display

 

t

–592.25

Portion of third month’s payment

 

 

applied to interest.

 

–190.22

Portion of third month’s payment

 

 

applied to principal.

t(or any key)

–190.22

Halts program execution.

Conditional Branching

Often there are situations when it is desirable for a program to be able to branch to different lines in program memory, depending on certain conditions. For example, a program used by an accountant to calculate taxes might need to branch to different program lines depending on the tax rate for the particular income level.

The hp 12c platinum provides two conditional test instructions that are used in programs for conditional branching:

zgotests whether the number in the X-register (represented by the x in the key symbol) is less than or equal to the number in the Y-register (represented by the y in the key symbol). As discussed in Appendix A, the number in the X-register is simply the number that would, if the calculator were in Run mode, be currently in the display; and the number in the Y-register is the number

that would, if the calculator were in Run mode, have been in the display when \ was pressed. For example, pressing 4\5 would place the number 4 in the Y-register and the number 5 in the X-register.

zgmtests whether the number in the X-register is equal to zero.

The possible results of executing either of these instructions are:

zIf the condition tested for is true when the instruction is executed, program execution continues sequentially with the instruction in the next line of program memory.

zIf the condition tested for is false when the instruction is executed, program execution skips the instruction in the next line of program memory and continues with the instruction in the following line.

File name: hp 12c pt_user's guide_English_HDPMF123E27

Page: 129 of 275

Printed Date: 2005/8/1

Dimension: 14.8 cm x 21 cm