introduction chapter 1 1/22/16. check zybooks completion click on the boxes for each section
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Introduction
Chapter 11/22/16
Check zyBooks Completion
Click on the boxes for each section.
Assignment• See my website for the new assignment.
Today's Topics
OutputParts of a C ProgramCommentsInputAlgorithmsErrors and Warnings
Outputprintf function is used to display output.Must include the i/o library in the program. #include <stdio.h>Now the printf function can be used.printf(“%d tons\n", 16);Output:16 tons%d is format for integers. Where tons is printed.
Displaying Text• \n is a new line character• If it is not there, the next output will
continue on the same line.
printf("Without Dennis Ritchie "); printf("there would be no\n"); printf("Steve Jobs.\n");
A Simple C ProgramA program is needed to figure out how many
pets we have, given the number of dogs and cats that includes. Write a program to set the number of cats and dogs. Output the number of pets.
The instructions in a program are called code.Here is the code:
Imagine! Java: Programming Concepts in Context by Frank M. Carrano, (c) Pearson Education - Prentice Hall, 2010
#include <stdio.h>//Program to add up the number of pets
int main(void){ int cats = 4; int dogs = 3;
int pets = cats + dogs;
printf("We have %d pets\n" , pets);
return 0;}
A Simple C Programmain function
• Where the execution begins. int main(void){ }• Block begins and ends with brace{ … } • Statements within block end with a ;
Tell processor what to do.
Imagine! Java: Programming Concepts in Context by Frank M. Carrano, (c) Pearson Education - Prentice Hall, 2010
Assignment Statementint cats = 4;• int cats declares a variable.
o A variable is a memory location.o Memory is a place to store values temporarily.
• cat = 4; sets cats to 4.• int pets = cats + dogs;o Does the addition on the right first.o Assigns the answer to pets.
CommentsDocuments the programComments
• Begin line with double slash //Ends with the end of the line.
• Span multiple lines between slash-star combination./* . . . . . . */
Imagine! Java: Programming Concepts in Context by Frank M. Carrano, (c) Pearson Education - Prentice Hall, 2010
return Statement
return 0;• Ends the program and gives control back to
operating system.
Questions
• What happens when a “\n” is put in the output?• Where do the statements in a C program
belong?• Give an example of an assignment
statement.
Input
Input Makes Program Useful Programs so far do one calculation
Example in dogyrs.c More useful if you can input human_yrs
doginput.c
scanf
scanf("%d", &human_yrs);
scanf – function name“%d” - input format, same as printf
formats& -- “address of” operator&human_yrs – where data will be stored.
scanf
Execution pauses until user enters a value and hits <enter>
Value input stored in variable(s)Prompt is recommended
printf to tell user input is expected. I'll put one in doginput.c
• #include <stdio.h> makes scanf available.
Find the Number of People
Write a program to figure how many people are touring Yosemite Park today. Ask for the number of people one tour bus can hold and the number of buses in the park. Output the total number of passengers.
#include <stdio.h>
int main(void){//Ask for the number of people on each bus int peopleOnBus; printf("People on one bus?"); scanf("%d", &peopleOnBus);//Ask for the number of buses int noBuses; printf("Number of Buses?"); scanf("%d", &noBuses);//Find total number of people int people = peopleOnBus * noBuses;//Output total number of people printf("%d people\n", people);
return 0;}
Login and Password
If you don't have a login, send me email. Contact me if you forget your password. Change your password to something easy
to remember. ssh -Y onyx
Login again passwd
Nothing shows while you are typing.
Questions
• What statement is used to handle input?• What preprocessor directive must be in
programs that have input or output?
Number of Meals Needed
A coding conference provides three meals for each participant. Write a program to input the number of participants then output the total number of meals needed.
• Write an algorithm with a partner• Along with your partner, code the program
using vim.– Print it and hand in a copy with both
names on it.
Errors and Warnings
Errors
• Syntax Error Violation of programming language rules. Caught by compiler. Program will not compile.
• Logic Error Error while program runs. For example, incorrect computation.
distance = rate/time;
Errors and Warnings
• Error prevents program from compiling• Warning means something might be
wrong. Try to get rid of it.
Questions
What kind of error is it?1.The compiler prints an error message because a semicolon(;) is missing.2. A program to convert Fahrenheit to Celcius gives incorrect results.3. The program compiles but the compiler gives a message about a possible problem.
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