Post on 03-Jun-2020
0
Computer Science 50Introduction to Computer Science I
Harvard College
David J. Malanmalan@post.harvard.edu
Week 1
1
Scratch versus C
2
Hello, C!#include <stdio.h>
int
main(int argc, char * argv[])
{
printf("hello, world\n");
}10000011 00000001 00010001 00000000 00111101 11111100 01110100 0011110100000000 01000000 00000000 00000000 00000000 00000000 00000000 0000000010010000 00000000 00000000 00000000 01010000 00000000 00000111 0011000000001011 00000001 00001011 00000011 00001010 00000000 00000000 0000000000000000 00100000 00000000 00000000 00000000 00000000 00000000 0000000000000000 00100000 00000000 00000000 00000000 00000000 00000000 0000000000000000 00000000 00000000 00000000 00000000 00000000 00000000 0000000001110000 00010000 00000000 00100000 00000001 00000000 00000000 0000000000000000 00000000 00000000 00100000 00000001 00000000 00000000 0000000000000000 00000000 00000000 01000000 00000001 00000000 00000000 0000000000000000 00100000 00000000 01000000 00000001 00000000 00000000 0000000011111111 11111111 11111111 11111111 11111111 11111111 11111111 1111111110010000 10000000 00000000 01000000 00000001 00000000 00000000 0000000000101110 01100100 01111001 01101110 01100001 01101101 01101001 0110001110110000 00000100 00000000 00100000 00000001 00000000 00000000 0000000010110000 00000100 00000000 00100000 00000001 00000000 00000000 0000000010100000 00000001 00000000 00000000 00000000 00000000 00000000 0000000010110000 00000100 00000000 00000000 00000000 00000000 00000000 0000000000000000 00000000 00000000 00000000 00000000 00000000 00000000 0000000000000000 00000000 00000000 00000000 00000000 00000000 00000000 0000000000000000 00000000 00000000 00000000 00000000 00100000 00000000 00000000[...]
3
nice.fas.harvard.edu
4
nice.fas.harvard.edu
5
nice.fas.harvard.edu
6
Some Commandscd
cp
ls
mkdir
mv
pwd
rm
7
Some More Commandsci
co
cs50submit
emacs
gcc
gdb
make
man
nano
sb
vi
8
How to Write a Program in C
1) nano hello1.c
2) gcc hello1.c
3) a.out
seehello1.c
9
How to Write a Program in C(with a better name)
1) nano hello1.c
2) gcc -o hello1 hello1.c
3) hello1
seehello1.c
10
main
int main(int argc, char * argv[]);
11
Standard Outputprintf
int printf(const char *format, ...);
seehttp://www.cppreference.com/stdio/printf.html
12
Escape Sequences\n
\r
\t
\"
\\
seehttp://www.cppreference.com/escape_sequences.html
13
VariablesTypes †
char
double
float
int
† long, short, signed, unsigned
seemath1.c
14
Format Strings%c
%d
%e
%E
%f
%s
%u
%x
seemath2.c, sizeof.c
http://www.cppreference.com/stdio/printf.html
15
Arithmetic Operators+
-
*
/
%
16
Precedence
Chart from http://www.difranco.net/cop2220/op-prec.htm.
17
Width and Precision †
%<width>.<precision>e
%<width>.<precision>E
%<width>.<precision>f
%<width>.<precision>s
† -, +
seemath3.c
http://www.cppreference.com/stdio/printf.html
18
VariablesTypes †
bool
string
† These are CS 50-specific.
seehello2.c
19
Standard Input †
char GetChar();
double GetDouble();
float GetFloat();
int GetInt();
string GetString();
† These are CS 50-specific.
seehello3.c, adder.c
20
How to Write a Program in C(using CS 50’s library)
1) nano hello3.c
2) gcc -o hello3 hello3.c -lcs50
3) hello3
seehello3.c
21
Fahrenheit to CelsiusC = (5/9) × (F – 32)
#include <cs50.h>
#include <stdio.h>
int
main(int argc, char * argv[])
{
}
22
Conditionsif
if (condition){
/* do this */}
23
Conditionsif-else
if (condition){
/* do this */}else{
/* do that */}
seeconditions1.c
24
Conditionsif-else if-else
if (condition){
/* do this */}else if (condition){
/* do that */}else{
/* do this other thing */}
seeconditions2.c
25
Boolean Expressionsif (condition || condition){
/* do this */}else{
/* do that */}
26
Boolean Expressionsif (condition && condition){
/* do this */}else{
/* do that */}
seenonswitch.c
27
Conditionsswitch
switch (expression){
case i:/* do this */break;
case j: /* do that */break;
default:/* do this other thing */
}
seeswitch{1,2}.c
28
Loopsfor
for (initializations; condition; updates){
/* do this again and again */}
seeprogress{1,2}.c
29
Loopswhile
while (condition){
/* do this again and again */}
seeprogress3.c
30
Loopsdo-while
do{
/* do this again and again */}while (condition)
seepositive.c
31
Computer Science 50Introduction to Computer Science I
Harvard College
David J. Malanmalan@post.harvard.edu
Week 1