C workshop Yuli Kaplunovsky - Today - Introduction to C Recommended book: The C programming Language / Kernighan & Ritchie

My first program #include void main() { printf("Hello World!\n"); } Output: Hello World!

C structure Function oriented (‘goto’ is not recommended) First function is always called main Contains many libraries (e.g. stdio.h, stdlib.h, math.h) with many predefined functions. CaSe SeNsItIvE (e.g. ‘Main’ instead of ‘main’ won’t work) ALWAYS USE: –Indentation –Meaningful names for functions and variables –Plenty of remarks

Variables int – an integer number maximum value is 2,147,483,647 (or 2^31) minimum value is -2,147,483,648 double – real number, represented as floating point (64 bits long) char – represents a single character

Variables sample #1 #include void main() { int I,J,K; I = 10; J = 20; K = I + J; printf("K is %d\n", K); } Output: K is 30

Variable sample #2 #include void main() { double X,Y,Z; X = 10.0; Y = 20.0; Z = X / Y; printf("Z is %g\n", Z); } Output: Z is 0.5

while #include /* Print Fahrenheit-Celsius table for fahr = 0, 20,.., 300 */ void main() { int fahr, celsius; int lower, upper, step; lower = 0; /* lower limit of temerature table */ upper = 300; /* upper limit */ step = 20; /* step size */ fahr = lower; while ( fahr <= upper ) { celsius = 5 * (fahr - 32) / 9; printf("%d\t%d\n", fahr, celsius ); fahr = fahr + step; } Output:

for Syntax: for ( initialization ; condition ; do ) { block } #include void main() { int I; printf("I = "); for ( I = 0 ; I < 10 ; I++ ) printf("%d, ", I ); printf("\n"); } Output: I = 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,

for - another example #include void main() { int fahr; for ( fahr = 0 ; fahr <= 300 ; fahr = fahr + 20 ) printf("%d %g\n", fahr, (5.0 / 9.0) * (fahr - 32) ); } Output:

if if ( condition ) { block #1 } else { block #2 } (optional) Example: if ( Y > X ) Z = X; else Z = Y; For comparisons use: > = == Important remark: a block should be surrounded with {} if it contains more than one command.

If - multiple conditions if ( (condition1 || condition2 ) && condition3)... Examples: if ( Y > X && Y > Z ) Z = X; int bTerminate; if ( I == 10 || bTerminate ) break; break is used to get out of for & while loops condition2 is FALSE when bTerminate is 0 and is TRUE when bTerminate is NOT 0

Functions Return-value function-name( parameters ) { … return value; } Calling the function: I = function-name( 10, 20 );

Function example #include int Add2( int A, int B ) { int C; C = A + B; return C; } void main() { int I; I = Add2( 10, 20 ); printf("Add2 function returns = %d\n", I); } Output: Add2 function returns = 30

Arrays ALWAYS start from 0 Last item is N-1 Example: int Ar[10]; Ar[0] = 22; Ar[9] = Ar[0] + 22; I = 4; Ar[I] = Ar[I+1];

#include // Guess what this program does... void main() { double X[10] = { 2, 4.2, 11.2, 3, 99.2, -23.2, 33, 11, 43, 9 }; double Y; int I, J; for ( I = 0 ; I < 9 ; I++ ) { for ( J = I+1 ; J < 10 ; J++ ) { if ( X[I] > X[J] ) { // Switch variables in array Y = X[I]; X[I] = X[J]; X[J] = Y; } // print results for ( I = 0 ; I < 10 ; I++ ) printf("%g, ", X[I]); } Output: -23.2, 2, 3, 4.2, 9, 11, 11.2, 33, 43, 99.2,