1. CS150 Introduction to Computer Science 1
Example
Write a program to read five integer numbers from a file, and calculate the sum.
Whenever you pass an ifstream or ofstream variable to a function, you must pass it by reference (i.e. &).
Why?
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CS150 Introduction to Computer Science 1

2. CS150 Introduction to Computer Science 1
Ch. 7 Data Types
We’ve seen:
ints: typically 32 bits, can be 16
floats: typically 32 bits
chars: typically 8 bits
New:
short: typically 16 bits
long: typically 64 bits
double: typically 64 bits
System dependent
Look at climit and cfloat on p. 350
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CS150 Introduction to Computer Science 1

3. CS150 Introduction to Computer Science 1
Characters
Characters stored in one byte
Represented by ASCII value
American Standard Code for Information Interchange
Characters are stored as an 8 bit int
Relationships
‘0’ < ‘1’ < ‘2’ < ‘3’ < ‘4’ < ‘5’ < ‘6’ < ‘7’ < ‘8’ < ‘9’
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CS150 Introduction to Computer Science 1

4. CS150 Introduction to Computer Science 1
Program
The printable characters have ASCII values in the range of 32 to 126. Write a C++ program segment that will print the printable character and its associated ASCII value 8 values per line.
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CS150 Introduction to Computer Science 1

5. CS150 Introduction to Computer Science 1
Type Casting
There are two ways to perform type casting
cout << (int) ‘a’;
Cout << int(‘a’);
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CS150 Introduction to Computer Science 1

6. CS150 Introduction to Computer Science 1
What is the Output?
int(‘d’)-int(‘a’)
char((int(‘M’) – int(‘A’)) + int(‘a’))
int(‘7’) – int(‘0’)
char(int(‘5’) + 1)
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CS150 Introduction to Computer Science 1

7. CS150 Introduction to Computer Science 1
Char Operations
Useful operations: islower, toupper, isdigit, islower, isspace, isupper, tolower
#include <ctype>
void todigit(char, &int); …
void todigit(char ch, &int num) {
if (isdigit(ch))
num = int(ch) - int (‘0’); }
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CS150 Introduction to Computer Science 1

8. CS150 Introduction to Computer Science 1
Char I/O Operations
Using cin, can we read in all possible chars?
We need some other operations
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CS150 Introduction to Computer Science 1

9. CS150 Introduction to Computer Science 1
Program
#include <iostream>
int main() {
char ch;
int count;
count = 0;
cin.get(ch);
while (!cin.eof())
count++; }
cout << "Number of characters = " << count << endl;
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CS150 Introduction to Computer Science 1

10. CS150 Introduction to Computer Science 1
Program
#include <iostream>
int main() {
char ch;
cin.get(ch);
while (!cin.eof())
cout.put(ch); }
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CS150 Introduction to Computer Science 1

11. CS150 Introduction to Computer Science 1
Program
#include <iostream>
int main() {
const char newline = '\n';
char ch;
cin.get(ch);
while (ch != newline && !cin.eof())
cout.put(ch); }
cout.put(newline);
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CS150 Introduction to Computer Science 1