Computer Programming 简明教程

1.	Go straight
2.	Drive half kilometer
3.	Take left
4.	Drive around one kilometer
5.	Search for KFC at your right side

print "Hello, World!"

1. Get a list of numbers L1, L2, L3....LN
2. Assume L1 is the largest, Largest = L1
3. Take next number Li from the list and do the following
4. If Largest is less than Li
5. Largest = Li
6. If Li is last number from the list then
7. Print value stored in Largest and come out
8. Else repeat same process starting from step 3

Start Icon → All Programs → Accessories → Notepad → Mouse Click on Notepad

#include <stdio.h>

int main() {
   /* printf() function to write Hello, World! */
   printf( "Hello, World!" );
}

Hello, World!

#include <stdio.h>

main() {
   printf("Hello, World!")
}

main.c: In function 'main':
main.c:7:1: error: expected ';' before '}' token
 }
 ^

public class HelloWorld {
   public static void main(String []args) {
      /* println() function to write Hello, World! */
      System.out.println("Hello, World!");
   }
}

Hello, World!

#  print function to write Hello, World! */
print "Hello, World!"

Hello, World!

#include <stdio.h>

int main() {
   int a;
   int b;
}

/* variable to store long value */
long a;

/* variable to store float value */
float b;

#include <stdio.h>

int main() {
   int a, b;
}

#include <stdio.h>

int main() {
   int a;
   int b;

   a = 10;
   b = 20;
}

#include <stdio.h>

int main() {
   int a;
   int b;

   a = 10;
   b = 20;

   printf( "Value of a = %d\n", a );
   printf( "Value of b = %d\n", b );
}

Value of a = 10
Value of b = 20

#include <stdio.h>

int main() {
   int a;
   int b;

   a = 10;
   b = 20;

   printf( "Value of a = %d and value of b = %d\n", a, b );
}

Value of a = 10 and value of b = 20

public class DemoJava {
   public static void main(String []args) {
      int a;
      int b;

      a = 10;
      b = 20;

      System.out.println("Value of a = " + a);
      System.out.println("Value of b = " + b);
      System.out.println("Value of a = " + a + " and value of b = " + b);
   }
}

Value of a = 10
Value of b = 20
Value of a = 10 and value of b = 20

a = 10
b = 20

print "Value of a = ", a
print "Value of b = ", b
print "Value of a = ", a, " and value of b = ", b

Value of a =  10
Value of b =  20
Value of a =  10  and value of b =  20

#include <stdio.h>

int main() {
   int a = 10;
   int b = 20;

   printf( "Value of a = %d and value of b = %d\n", a, b );
}

Value of a = 10 and value of b = 20

2 + 3

P(x) = x4 + 7x3 - 5x + 9.

#include <stdio.h>

int main() {
   int a, b, c;

   a = 10;
   b = 20;

   c = a + b;
   printf( "Value of c = %d\n", c);

   c = a - b;
   printf( "Value of c = %d\n", c);

   c = a * b;
   printf( "Value of c = %d\n", c);

   c = b / a;
   printf( "Value of c = %d\n", c);

   c = b % a;
   printf( "Value of c = %d\n", c);
}

Value of c = 30
Value of c = -10
Value of c = 200
Value of c = 2
Value of c = 0

A = 20
B = 10

(A > B)

#include <stdio.h>

int main() {
   int a, b;

   a = 10;
   b = 20;

   /* Here we check whether a is equal to 10 or not */
   if( a == 10 ) {

      /* if a is equal to 10 then this body will be executed */
      printf( "a is equal to 10\n");
   }

   /* Here we check whether b is equal to 10 or not */
   if( b == 10 ) {

      /* if b is equal to 10 then this body will be executed */
      printf( "b is equal to 10\n");
   }

   /* Here we check if a is less b than or not */
   if( a < b ) {

      /* if a is less than b then this body will be executed */
      printf( "a is less than b\n");
   }

   /* Here we check whether a and b are not equal */
   if( a != b ) {

      /* if a is not equal to b then this body will be executed */
      printf( "a is not equal to b\n");
   }
}

a is equal to 10
a is less than b
a is not equal to b

#include <stdio.h>

int main() {
   int a = 1;
   int b = 0;

   if ( a && b ) {

      printf("This will never print because condition is false\n" );
   }
   if ( a || b ) {

      printf("This will be printed print because condition is true\n" );
   }
   if ( !(a && b) ) {

      printf("This will be printed print because condition is true\n" );
   }
}

This will be printed print because condition is true
This will be printed print because condition is true

public class DemoJava {
   public static void main(String []args) {
      int a, b, c;

      a = 10;
      b = 20;

      c = a + b;
      System.out.println("Value of c = " + c );

      c = a - b;
      System.out.println("Value of c = " + c );

      c = a * b;
      System.out.println("Value of c = " + c );

      c = b / a;
      System.out.println("Value of c = " + c );

      c = b % a;
      System.out.println("Value of c = " + c );

      if( a == 10 ) {

         System.out.println("a is equal to 10" );
      }
   }
}

Value of c = 30
Value of c = -10
Value of c = 200
Value of c = 2
Value of c = 0
a is equal to 10

a = 10
b = 20

c = a + b
print "Value of c = ", c

c = a - b
print "Value of c = ", c

c = a * b
print "Value of c = ", c

c = a / b
print "Value of c = ", c

c = a % b
print "Value of c = ", c

if( a == 10 ):
   print "a is equal to 10"

Value of c =  30
Value of c =  -10
Value of c =  200
Value of c =  0
Value of c =  10
a is equal to 10

if(boolean_expression) {

   /* Statement(s) will execute if the boolean expression is true */
} else {

  /* Statement(s) will execute if the boolean expression is false */
}

#include <stdio.h>

int main() {
   int x = 45;

   if( x > 95) {

      printf( "Student is brilliant\n");
   } else {
      printf( "Student is not brilliant\n");
   }
}

Student is not brilliant

if(boolean_expression 1) {

   /* Executes when the boolean expression 1 is true */
}
else if( boolean_expression 2) {

   /* Executes when the boolean expression 2 is true */
}
else if( boolean_expression 3) {

   /* Executes when the boolean expression 3 is true */
} else {

   /* Executes when the none of the above condition is true */
}

#include <stdio.h>

int main() {
   int x = 45;

   if( x > 95) {
      printf( "Student is brilliant\n");
   }
   else if( x < 30) {
      printf( "Student is poor\n");
   }
   else if( x < 95 && x > 30 ) {
      printf( "Student is average\n");
   }
}

Student is average

switch(expression){
   case ONE :
      statement(s);
      break;
   case TWO:
      statement(s);
      break;
   ......

   default :
      statement(s);
}

#include <stdio.h>

int main() {
   int x = 2;

   switch( x ){
      case 1 :
         printf( "One\n");
         break;
      case 2 :
         printf( "Two\n");
         break;
      case 3 :
         printf( "Three\n");
         break;
      case 4 :
         printf( "Four\n");
         break;
      default :
         printf( "None of the above...\n");
   }
}

Two

public class DemoJava {
   public static void main(String []args) {
      int x = 45;

      if( x > 95) {
         System.out.println( "Student is brilliant");
      }
      else if( x < 30) {
         System.out.println( "Student is poor");
      }
      else if( x < 95 && x > 30 ) {
         System.out.println( "Student is average");
      }
   }
}

Student is average

x = 45

if x > 95:
   print "Student is brilliant"
elif x < 30:
   print "Student is poor"
elif x < 95 and x > 30:
   print "Student is average"

print "The end"

Student is average
The end

while ( condition ) {
   /*....while loop body ....*/
}

do {
   /*....do...while loop body ....*/
}
while ( condition );

#include <stdio.h>

int main() {
   int i = 0;

   do {
      printf( "Hello, World!\n");
      i = i + 1;
   }
   while ( i < 5 );
}

Hello, World!
Hello, World!
Hello, World!
Hello, World!
Hello, World!

break;

#include <stdio.h>

int main() {
   int i = 0;
   do {
      printf( "Hello, World!\n");
      i = i + 1;

      if( i == 3 ) {
         break;
      }
   }
   while ( i < 5 );
}

Hello, World!
Hello, World!
Hello, World!

continue;

#include <stdio.h>

int main() {
   int i = 0;
   do {
      if( i == 3 ) {
         i = i + 1;
         continue;
      }
      printf( "Hello, World!\n");
      i = i + 1;
   }
   while ( i < 5 );
}

Hello, World!
Hello, World!
Hello, World!
Hello, World!

public class DemoJava {
   public static void main(String []args) {
      int i = 0;

      while ( i < 5 ) {
         System.out.println("Hello, World!");
         i = i + 1;
      }
   }
}

i = 0

while (i < 5):
   print "Hello, World!"
   i = i + 1
print "Loop ends"

Hello, World!
Hello, World!
Hello, World!
Hello, World!
Hello, World!
Loop ends

#include <stdio.h>
#include <math.h>

int main() {
   short  s;
   int    i;
   long   l;
   float  f;
   double d;

   printf( "sin(s): %f\n", sin(10));
   printf( "abs(i): %f\n", abs(1000));
   printf( "floor(f): %f\n", floor(230.47));
   printf( "sqrt(l): %f\n", sqrt(1000000));
   printf( "pow(d, 2): %f\n", pow(2.374, 2));
}

sin(s): -0.544021
abs(i): -0.544021
floor(f): 230.000000
sqrt(l): 1000.000000
pow(d, 2): 5.635876

public class DemoJava {
   public static void main(String []args) {
      short  s;
      int    i;
      long   l;
      float  f;
      double d;

      s = 10;
      i = 1000;
      l = 1000000L;
      f = 230.47f;
      d = 30949.374;

      System.out.format( "s: %d\n", s);
      System.out.format( "i: %d\n", i);
      System.out.format( "l: %d\n", l);
      System.out.format( "f: %f\n", f);
      System.out.format( "d: %f\n", d);
   }
}

s: 10
i: 1000
l: 1000000
f: 230.470001
d: 30949.374000

s = 10
i = 1000
l = 1000000
f = 230.47
d = 30949.374

print "s: ", s
print "i: ", i
print "l: ", l
print "f: ", f
print "d: ", d

s:  10
i:  1000
l:  1000000
f:  230.47
d:  30949.374

char ch = '\n';

char ch = '\1';

#include <stdio.h>

int main() {
   char  ch1;
   char  ch2;
   char  ch3;
   char  ch4;

   ch1 = '\t';
   ch2 = '\n';

   printf( "Test for tabspace %c and a newline %c will start here", ch1, ch2);
}

Test for tabspace     and a newline
will start here

public class DemoJava {
   public static void main(String []args) {
      char  ch1;
      char  ch2;
      char  ch3;
      char  ch4;

      ch1 = 'a';
      ch2 = '1';
      ch3 = '$';
      ch4 = '+';

      System.out.format( "ch1: %c\n", ch1);
      System.out.format( "ch2: %c\n", ch2);
      System.out.format( "ch3: %c\n", ch3);
      System.out.format( "ch4: %c\n", ch4);
   }
}

ch1:  a
ch2:  1
ch3:  $
ch4:  +

ch1 = 'a';
ch2 = '1';
ch3 = '$';
ch4 = '+';

print "ch1: ", ch1
print "ch2: ", ch2
print "ch3: ", ch3
print "ch4: ", ch4

ch1:  a
ch2:  1
ch3:  $
ch4:  +

type arrayName [ arraySize ];

int number[10];

int number[5] = {10, 20, 30, 40, 50};

int number[] = {10, 20, 30, 40, 50};

number[4] = 50;

int var = number[9];

#include <stdio.h>

int main () {
   int number[10]; /* number is an array of 10 integers */
   int i = 0;

   /* Initialize elements of array n to 0 */
   while( i < 10 ) {

      /* Set element at location i to i + 100 */
      number[ i ] = i + 100;
      i = i + 1;
   }

   /* Output each array element's value */
   i = 0;
   while( i < 10 ) {

      printf("number[%d] = %d\n", i, number[i] );
      i = i + 1;
   }

   return 0;
}

number[0] = 100
number[1] = 101
number[2] = 102
number[3] = 103
number[4] = 104
number[5] = 105
number[6] = 106
number[7] = 107
number[8] = 108
number[9] = 109

public class DemoJava {
   public static void main(String []args) {
      int[] number = new int[10];
      int i = 0;

      while( i < 10 ) {

         number[ i ] = i + 100;
         i = i + 1;
      }

      i = 0;
      while( i < 10 ) {
         System.out.format( "number[%d] = %d\n", i, number[i] );
         i = i + 1;
      }
   }
}

number[0] = 100
number[1] = 101
number[2] = 102
number[3] = 103
number[4] = 104
number[5] = 105
number[6] = 106
number[7] = 107
number[8] = 108
number[9] = 109

# Following defines an empty list.
number = []
i = 0

while i < 10:
   # Appending elements in the list
   number.append(i + 100)
   i = i + 1

i = 0
while i < 10:
   # Accessing elements from the list
   print "number[", i,  "] = ", number[ i ]
   i = i + 1

number[ 0 ] =  100
number[ 1 ] =  101
number[ 2 ] =  102
number[ 3 ] =  103
number[ 4 ] =  104
number[ 5 ] =  105
number[ 6 ] =  106
number[ 7 ] =  107
number[ 8 ] =  108
number[ 9 ] =  109

public class DemoJava {
   public static void main(String []args) {
      String str = new String("Hello");
      System.out.println( "String = " + str );
   }
}

String = Hello

var1 = 'Hello World!'
var2 = "Python Programming"

print "var1 = ", var1
print "var2 = ", var2

var1 =  Hello World!
var2 =  Python Programming

var1 = 'Hello World!'
var2 = "Python Programming"

print "var1[0]: ", var1[0]
print "var2[1:5]: ", var2[1:5]

var1[0]:  H
var2[1:5]:  ytho

return_type function_name( parameter list ) {
   body of the function

   return [expression];
}

#include <stdio.h>

int getMax( int set[] ) {
   int i, max;

   max = set[0];
   i = 1;
   while( i < 5 ) {
      if( max <  set[i] ) {
         max = set[i];
      }
      i = i + 1;
   }
   return max;
}
main() {
   int set1[5] = {10, 20, 30, 40, 50};
   int set2[5] = {101, 201, 301, 401, 501};
   int max;

   /* Process first set of numbers available in set1[] */
   max = getMax(set1);
   printf("Max in first set = %d\n", max );

   /* Now process second set of numbers available in set2[] */
   max = getMax(set2);
   printf("Max in second set = %d\n", max );
}

Max in first set = 50
Max in second set = 501

public class DemoJava {
   public static void main(String []args) {
      int[] set1 = {10, 20, 30, 40, 50};
      int[] set2 = {101, 201, 301, 401, 501};
      int max;

      /* Process first set of numbers available in set1[] */
      max = getMax(set1);
      System.out.format("Max in first set = %d\n", max );

      /* Now process second set of numbers available in set2[] */
      max = getMax(set2);
      System.out.format("Max in second set = %d\n", max );
   }
   public static int getMax( int set[] ) {
      int i, max;
      max = set[0];
      i = 1;

      while( i < 5 ) {
         if( max <  set[i] ) {
            max = set[i];
         }
         i = i + 1;
      }
      return max;
   }
}

Max in first set = 50
Max in second set = 501

def function_name( parameter list ):
   body of the function

   return [expression]

def getMax( set ):
   max = set[0]
   i = 1

   while( i < 5 ):
      if( max <  set[i] ):
         max = set[i]

      i = i + 1
   return max

set1 = [10, 20, 30, 40, 50]
set2 = [101, 201, 301, 401, 501]

# Process first set of numbers available in set1[]
max = getMax(set1)
print "Max in first set = ", max

# Now process second set of numbers available in set2[]
max = getMax(set2)
print "Max in second set = ", max

Max in first set =  50
Max in second set =  501

FILE *fopen( const char * filename, const char * mode );

 int fclose( FILE *fp );

int fputc( int c, FILE *fp );

int fputs( const char *s, FILE *fp );

#include <stdio.h>

int main() {
   FILE *fp;

   fp = fopen("/tmp/test.txt", "w+");
   fprintf(fp, "This is testing for fprintf...\n");
   fputs("This is testing for fputs...\n", fp);
   fclose(fp);
}

int fgetc( FILE * fp );

char *fgets( char *buf, int n, FILE *fp );

#include <stdio.h>

main() {

   FILE *fp;
   char buff[255];

   fp = fopen("/tmp/test.txt", "r");
   fscanf(fp, "%s", buff);
   printf("1 : %s\n", buff );

   fgets(buff, 255, (FILE*)fp);
   printf("2: %s\n", buff );

   fgets(buff, 255, (FILE*)fp);
   printf("3: %s\n", buff );
   fclose(fp);
}

1 : This
2 : is testing for fprintf...

3 : This is testing for fputs...

import java.io.*;

public class DemoJava {
   public static void main(String []args) throws IOException {
      File file = new File("/tmp/java.txt");

      // Create a File
      file.createNewFile();

      //  Creates a FileWriter Object using file object
      FileWriter writer = new FileWriter(file);

      // Writes the content to the file
      writer.write("This is testing for Java write...\n");
      writer.write("This is second line...\n");

      // Flush the memory and close the file
      writer.flush();
      writer.close();

      // Creates a FileReader Object
      FileReader reader = new FileReader(file);
      char [] a = new char[100];

      // Read file content in the array
      reader.read(a);
      System.out.println( a );

      // Close the file
      reader.close();
   }
}

This is testing for Java write...
This is second line...

# Create a new file
fo = open("/tmp/python.txt", "w")

# Writes the content to the file
fo.write( "This is testing for Python write...\n");
fo.write( "This is second line...\n");

# Close the file
fo.close()

# Open existing file
fo = open("/tmp/python.txt", "r")

# Read file content in a variable
str = fo.read(100);
print str

# Close opened file
fo.close()

This is testing for Python write...
This is second line...