BIHAR

                              NISHANT KUMAR
                                http://ascpn.blogspot.in/                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       Summary of basic C++-commands
Compiling
To compile a C++-program, you can use either g++ or c++.
g++ -o executable filename.out sourcefilename.cc
c++ -o executable filename.out sourcefilename.cc
e.g. g++ -o C++sample inout.out C++sample inout.cc
For the following commands you can find at the end of this summary sample
programs.
Each command in C++ is followed by “;” . Carriage return has no meaning
in C++.
Comments
Essential for the writing of clear programs are comments, which are explana-
tions for your program, and which are ignored by the compiler.
/* . . . */ puts the text . . . into comment (more than one line possible)
// . . . puts text . . . for rest of same line into comment
Data Types
Data Type Declaration (Example) Assignment (Example)
integer short i1,i2; i1 = 3;
int i1,i2;
long i1,i2;
unsigned i1,i2;
unsigned long i1,i2;
real float f1,f2; f1 = 3.2; f2 = 2.1E-3;
double f1,f2;
long double f1,f2;
single character char c1,c2; c1 = ’R’
string of characters string s1,s2; s1 = ”Farmer”
logical bool b1,b2; b1 = true; b2 = false
Input And Output
Input/Output With Screen:
To be able to use the following commands you need to write
#include <iostream>
using namespace std;
at the beginning of your program:
output: cout << ”string of characters”;
cout << variable; << endl;
input: cin >> variable;
Input/Output With Files:
To be able to use the following commands you need to write
#include <fstream> at the beginning of your program:
output: ofstream outfilevariable ( ”outputfilename”,ios::out);
outfilevariable << . . . will write into file with name outputfilename
input: ifstream infilevariable ( ”inputfilename”,ios::in);
infilevariable >> . . . will read from file with name outputfilename
Arithmetic Calculations
Operations: + − ∗ /
Functions:
To be able to use all of the following functions you need to to write at the
beginning of your program:
#include <cmath>
#include <cstdlib>
pow(x,y) xy
sin(x)
cos(x)
tan(x)
asin(x) sin−1(x) in range [− /2, /2]
acos(x) cos−1(x) in range [0, ]
atan(x) tan−1(x) in range [− /2, /2]
sinh(x)
cosh(x)
tanh(x)
exp(x) ex
log(x) ln(x)
sqrt(x) √x
fabs(x) |x|
floor(x) largest integer not greater than x; example: floor(5.768) = 5
ceil(x) smallest integer not less than x; example: ceil(5.768) = 6
fmod(x,y) floating-point remainder of x/y with the same sign as x
x % y remainder of x/y, both x and y are integers; example: 7%5=2
Decision Statements
Comparison Operators:
== = example: i1 == i2
!= 6= i1 != i2
> > i1 > i2
< < i1 < i2
>= ≥ i1 >= i2
<= ≤ i1 <= i2
&& and (i1 != i2)&& (i1 == i3)
|| and/or (i1 == i2) || (i1 == i3)
Statements:
if( condition ) {
statements
}
if( condition ) {
statements
}
else {
statements
}
if( condition ) {
statements
}
else if {
statements
}
else {
statements
}
switch ( casevariable ) {
case value1a:
case value1b:
{statements}
break;
case value2a:
case value2b:
{statements}
break;
default:
{statements}
}
Repetitions
while (conditions) {
statements
}
for ( init; conditions; update ){
statements
}
do {
statements these statements are done before the while statement check
} while ( condition) ;
functions
A function is a set of commands. It is useful to write a user-defined function,
i.e. your own function, whenever you need to do the same task many times in
the program. All programs start execution at the function main. For Functions
you need steps 1-3:
Step 1: At the beginning of your program you need to declare any functions:
function type function name (types of parameter list);
example 1: double feetinchtometer (int,double);
example 2: void metertofeetinch (double, int&, double&);
The function type declares which variable is passed back from the function
(void means none via the function type). The variables without “&” are all
input parameters, i.e. only passed to the function and are not changed within
the function. The variables with “&” may be passed both to and from the
function and may be changed in the function.
Step 2: In the program you use the function with:
function name (actual parameter list);
example 1: feetinchtometer(5.0,3.2);
example 2: metertofeetinch(1.3,feet,inch);
Step 3: After main { . . . } define your function:
function type function name (parameter types and names) { declarations and
statements }
example 1: double feetinchtometer(int feet, double inch){ . . .};
example 2: void metertofeetinch (double m, int& feet, double& inch){. . .};
Arrays
Data Type Declaration (Example) Assignment (Example)
array int street[100]; street[0]=0; street[50]=7;
double matrix[7]; matrix[6]=3.2;
etc. etc.
multidim. array int lattice[10][10]; lattice[0][1]=1;
double wateruse[5][3][2]; wateruse[3][1][0]=1.2;
etc. etc.