The Software Construction Process

Computer System Components Internet Primary Storage (RAM) Network Interface Devices (Modem, Network Card) 01001101 10110101 11011001 10110100 00101011 01011001 10101010 01011011 10100110 01001011 Output Devices (Monitor, Printer) Input Devices (Mouse, Keyboard) Communications Bus Secondary Storage (Hard Drive, CD-ROM Drive) Central Processing Unit (Microprocessor)

A Software Requirement Develop a program that finds and prints all numbers between 1 and 10,000 that are divisible by both 7 and 3. For each number found, display the number and the product of the two quotients.

The Requirement and the Design Set number to 1 Develop a program that finds and prints all numbers between 1 and 10,000 that are divisible by both 7 and 3. For each number found, display the number and the product of the two quotients. No Number less than or equal to 10,000 Yes No Number divisible by 7 Yes No Number divisible by 3 Yes Print number information Increment number by 1 F

Boards, Tubes, and Patch Cables Application Program 01001101 10110101 11011001 10110100 00101011 01011001 10101010 01011011 10100110 01001011

Setting Switches Application Program 01001101 10110101 11011001 10110100 00101011 01011001 10101010 01011011 10100110 01001011

I/O Devices and Operating System 01010101 10101010 10101110 01001011 Operating System 01001101 10110101 11011001 10110100 00101011 01011001 10101010 01011011 10100110 01001011 Application Program

Assembly Language, Monitor, and Keyboard 01010101 10101010 10101110 01001011 Operating System 10111010 10101010 01011011 Assembler 01001101 10110101 11011001 10110100 00101011 01011001 LOOP: LOAD A, R1 LOAD 7, R2 TEST R1, R2 BRZ LOOP Application Program

Compiler (Syntax and Semantics) 01010101 10101010 Operating System 10111010 10101110 01001011 #include <stdio.h> int main (void) { int anAnswer; float aValue; anAnswer = aValue / 3; printf(“%d\n”,anAnswer); return 0; } Assembler 10101011 00101010 01101011 Compiler 11011001 10110100 00101011 01011001 Application Program

Algorithm in C Source Code aNumber = LOWNUMBER; while (aNumber <= HIGHNUMBER) { firstQuotient = aNumber / FIRSTDIVISOR; if ( (aNumber % FIRSTDIVISOR) == 0 ) { secondQuotient = aNumber / SECONDDIVISOR; if ( (aNumber % SECONDDIVISOR) == 0) { theProduct = firstQuotient * secondQuotient; printf("%d %7.2f %7.2f %8.2f\n",aNumber, firstQuotient, secondQuotient, theProduct); } // End if } // End if aNumber++; // Increment aNumber by one Note: This is only a portion of the complete C program

From Requirements to Running Program Design Fundamentals Software Requirements Design Method Coding Standards Software Design Text Editor C Header Files program.c (Source Code) Compiler (and Preprocessor) Function Libraries program.o (Object Code) Linker Input/Output Facilities program.exe (Executable Code) Operating System

Software Construction Process Requirements 1 DESIGN COMPILE 2 3 8 EDIT and SAVE 4 A BASELINE LINK E B D C 7 5 TEST and SQA RUN 6 Note: See next slide for meanings of A - E

Categories of Errors A: Compiler errors – doesn’t follow preprocessor or C syntax B: Linker errors – functions declared but not defined; no main function; function library not found C: Run-time errors – segmentation fault; out-of-range errors; wrong data types D: Logic errors – wrong use of control statements; errors in function arguments; algorithm coded incorrectly E: Design errors – doesn’t follow design or satisfy requirements; design has flaws 