COP 3275
COMPUTER
PROGRAMMING
USING C
Instructor: Diego Rivera-Gutierrez
djrg@cise.ufl.edu http://cise.ufl.edu/~djrg/
https://ufcprog2015.wordpress.com/
ADMINISTRATIVE STUFF
• Not so new rule: whenever you participate tell me your
name!
• Reminder: Second quiz this Friday (29th)
• Format likely similar to 1st quiz. If you have concerns
please send them my way.
• Homework #2 due Monday (June 1st)
• Homework #3 likely to be assigned on Friday (29th)
ADMINISTRATIVE STUFF
• Homework #2:
• We will go into detail of my post later today (with
examples).
• The basics:
• When reading the hours, minutes, and seconds use %d not
%i.
• To display a particular number of characters use .<number>
between % and the letter. As in %.2d.
BUNCH OF STUFF WE
HAVEN’T COVERED
AKA Programming in C Potpurri
SWITCH STATEMENTS
switch(<expression>) {
case <value-1>:
<program-statement>
<program-statement>
break;
case <value-2>:
<program-statement>
<program-statement>
break;
…
…
case <value-n>:
<program-statement>
<program-statement>
break;
default:
<program-statement>
}
#include <stdio.h>
int main(void) {
float operand1 = 0.0f, operand2 = 0.0f, result = 0.0f;
char operator = '\0';
printf("Input the operation you want to evaluate: ");
scanf(“%f %c %f", &operand1, &operator, &operand2);
//
with what we know, we could do:
switch(operator) {
case '+':
result = operand1 + operand2;
break;
case '-':
result = operand1 - operand2;
break;
case 'x':
printf(“Warning the recommended operator is * not x\n“);
case '*':
result = operand1 * operand2;
break;
case '/':
result = operand1 / operand2;
break;
default:
printf(“Unknown operator %c\n“, operator);
}
printf("The result is: %f\n“, result);
return 0;
}
#include <stdio.h>
int main(void) {
float operand1 = 0.0f, operand2 = 0.0f, result = 0.0f;
char operator = '\0';
printf("Input the operation you want to evaluate: ");
scanf(“%f %c %f", &operand1, &operator, &operand2);
//
with what we know, we could do:
switch(operator) {
case '+':
result = operand1 + operand2;
break;
case '-':
result = operand1 - operand2;
break;
case 'x':
printf(“Warning the recommended operator is * not x\n“);
case '*':
result = operand1 * operand2;
break;
case '/':
result = operand1 / operand2;
break;
default:
printf(“Unknown operator %c\n“, operator);
}
printf("The result is: %.2f\n“, result);
return 0;
}
TERNARY OPERATOR CONDITIONAL OPERATOR
<condition>? <expression if true> : <expression if false>;
• This is useful to assign a variable a value for example:
float result = operator == ‘+’? operand1 + operand2 :
operand1 – operand2;
float result = (operator == ‘+’)?(operand1 + operand2)
: (operand1 – operand2) ;
REGARDING PARENTHESIS
AND THE TERNARY
OPERATOR
• I said last week that confusing parenthesis wouldn’t be
part of quizzes and I stand by that.
• Given an exercise there will always be parenthesis
around expressions to tell you what gets executed first,
but you will need to be able to follow it.
• For example:
float result = (operator == ‘+’) ?
(operand1 + operand2):(operand1 – operand2) ;
float result = (op == ‘+’) ? (o1 + o2):(o1 – o2) ;
Could also be:
float result = (op == ‘+’) ? (o1 + o2) :
( (op == '-') ? (o1 – o2) : (o1 * o2) ) ;
And I expect you to be able to follow the logic.
ASCII TABLE
• American Standard Code for Information Interchange
(ASCII).
• Starndard character-encoding scheme.
• Not the only one!
• By far the most common in C
DIFFERENCE BETWEEN
++X AND X++
• Last week we covered the operators ++ and --.
• The simple explanation was that
x++ is roughly equivalent to x = x + 1;
y-- is roughly equivalent to y = y – 1;
• Turns out the expressions ++x and --y are also valid.
• What’s the difference?
• Let’s use it in a more complicated expression:
int x = 3;
int n = 5 % 3 – (x++) + 2;
++X VS X++
int x = 3;
int n = 5 % 3 – (x++) + 2;
•
•
•
•
•
•
•
•
5%3=?
5%3=2
x++ = ?
Could be x++ = 3 or x++ = 4.
We only know that after the expression x will be 4
So n could be
2–3+3=2
or
2–4+3=1
Let’s test it.
#include <stdio.h>
int main(void) {
int x = 3;
int n = 5%3 – (x++) + 2;
printf("x = %d\n", x);
printf("n = %d\n", n);
return 0;
}
#include <stdio.h>
int main(void) {
int x = 3;
int n = 5%3 – (x++) + 2;
printf("x = %d\n", x); //this should be x = 4
printf("n = %d\n", n); //what should this be?
return 0;
}
#include <stdio.h>
int main(void) {
int x = 3;
int n = 5%3 – (++x) + 2;
printf("x = %d\n", x); //this should be x = 4
printf("n = %d\n", n); //what should this be?
return 0;
}
TYPE SPECIFIERS
So, can I have a infinitely large number stored in a variable of type int?
Specifier
long
long long
short
unsigned
signed
SIZE IN MEMORY OF
DIFFERENT TYPES
• There is an operator called sizeof.
• One parameter: a type.
• Returns an unsigned value that uses the %zu value to
printf.
sizeof
• For example:
• sizeof(int);
WHAT DO COMPUTERS DO
BETTER THAN HUMANS?
LOOPING
• Repetitive stuff.
•
•
•
•
•
•
•
•
Compute sum of many numbers
Generate a list of powers of a number
Work with an array of numbers
Work with an array of strings
Turn based games
Display a video
Video games
Execute a program
LOOPING
• Three structures. Equivalent in computational power.
• for statement
for(<init statement> ; <loop condition> ; <loop expression>)
<program statement>
• while statement
while(<loop condition>)
<program statement>
• Do-while statement
do
<program statement>
while (<loop condition>);
BETTER LOOPING – SERIOUSLY
GUYS USE PROTECTION
• Three structures. Equivalent in computational power.
• for statement
BRACKETS
for(<init statement> ; <loop condition> ; <loop expression>) {
<program statements>
}
• while statement
while(<loop condition>) {
<program statements>
}
• Do-while statement
do {
<program statements>
}while (<loop condition>);