Some Imp. Concepts And Basics Of C

#include <stdio.h> void main() { printf("\"It's freezing in here,\" he said coldly."); }

/* Program Characters and numbers */ #include <stdio.h> void main() { char first = 'A'; char second = 65; printf("\n printf("\n printf("\n printf("\n

letter number letter number

looks looks looks looks

like %c", first); like %d", first); like %c", second); like this %d\n", second);

} /* Program Finding the limits */ #include <stdio.h> #include #include void main() { clrscr(); printf("char store values from %d to %d", CHAR_MIN, CHAR_MAX); printf("\nshort store values from %d to %d", SHRT_MIN, SHRT_MAX); printf("\nint store values from %d to %d", INT_MIN, INT_MAX); printf("\nlong store values from %ld to %ld",LONG_MIN, LONG_MAX); printf("\n\n smallest non-zero value of type float is %.3f",FLT_MIN); printf("\n largest value of type float is %.3f", FLT_MAX); printf("\nsmallest non-zero value of type double is %.3f",DBL_MIN); printf("\n largest value of type double is %.3f", DBL_MAX); }

/* Program Finding the size of a type #include <stdio.h>

*/

void main() { clrscr(); printf("\nchar occupy %d bytes", sizeof(char)); printf("\nshort occupy %dbytes",sizeof(short)); printf("\nint occupy %d bytes", sizeof(int)); printf("\nlong occupy %d bytes",sizeof(long)); printf("\n float occupy %d ytes",sizeof(float)); printf("\n double occupy %d bytes", sizeof(double)); getch(); } /* Program Testing letters the easy way */ #include <stdio.h> void main() { char letter =0; clrscr(); printf("Enter an upper case letter:"); scanf(" %c", &letter); if ((letter >= 'A') && (letter <= 'Z')) { letter += 'a'-'A'; printf("You entered an upper-case %c.\n", letter); } else printf("You did not enter an uppercase letter.\n"); getch(); }

/*Example A calculator*/ #include <stdio.h> void main() { float number1 = 0.0; float number2 = 0.0; char operation ; clrscr(); printf("\nEnter the calculation\n"); scanf("%f %c %f", &number1, &operation, &number2); switch(operation) { case '+': printf("= %f\n", number1 + number2); break; case '-': printf("= %f\n", number1 - number2); break; case '*': printf("= %f\n", number1 * number2); break; case '/': if(number2 == 0) printf("\n\n\aDivision by zero error!\n"); else printf("= %f\n", number1 / number2); break; case '%': if((int)number2 == 0) printf("\n\n\aDivision by zero error!\n"); else printf("= %d\n", (int)number1 % (int)number2); break; default: printf("\n\n\aIllegal operation!\n"); } getch(); }

/*A calculator that allows multiple calculations */ #include <stdio.h> void main() { double number1 = 0.0; double number2 = 0.0; char operation ; char answer; start: printf("\nEnter the calculation as number operator number\n"); scanf("%lf %c %lf", &number1, &operation, &number2); /* Code to check the input goes here */ switch(operation) { case '+': printf("= %lf\n", number1 + number2); break; case '-': printf("= %lf\n", number1 - number2); break; case '*': printf("= %lf\n", number1 * number2); break; case '/': if(number2 == 0) printf("\n\n\aDivision by zero error!\n"); else printf("= %lf\n", number1 / number2); break; case '%': if((long)number2 == 0) printf("\n\n\aDivision by zero error!\n"); else printf("= %ld\n", (long)number1 % (long)number2); break; default: printf("\n\n\aIllegal operation!\n"); } printf("\n Do you want to do another calculation? (y or n): "); scanf(" %c", &answer); if(answer == 'y' || answer == 'Y') goto start; }

#include <stdio.h> main() { int digit = 1; clrscr(); while (digit <= 10) { printf ("%d\t", digit ) ; ++digit; } getch(); } #include <stdio.h> main() { int digit = 1; clrscr(); while (digit <= 10) { printf ("%d\t", digit ) ; digit++; } getch(); } #include <stdio.h> main() { int digit =1; clrscr(); while (digit <= 10) printf ( "%d\t", digit++) ; getch(); }

#include <stdio.h> main() { int digit =1; clrscr(); while (digit <= 10) printf ( "%d\t", ++digit) ; getch(); }

/* calculate the average of n numbers */ #include <stdio.h> main() { int n, count = 1; float x, average, sum = 0; clrscr(); printf("How many numbers? " ) ; scanf ("%d", &n) ; while (count <= n) { printf ( " x = " ) ; scanf("%f", &x); sum += x; ++count; } /* calculate the average and display the answer */ average = sum/n; printf("\nThe average i s %.2f\n", average); getch(); } #include <stdio.h> void main() { int sum = 0; int i = 1; int count = 0; clrscr(); printf("\nEnter the number of integers you want to sum: "); scanf("%d", &count); while(i <= count) sum += i++; printf("Total of the first %d numbers is %d\n", count, sum); printf("average=%.2f",(float)sum/count); getch(); }

#include <stdio.h> main() { int digit = 1; clrscr(); do { printf("%d\t", digit++); }while (digit <= 10); getch(); } #include <stdio.h> main() { int digit = 1; do { printf("%d\t", ++digit); }while (digit <= 10); getch(); } #include <stdio.h> void main( void ) { int counter = 1; clrscr(); do { printf( "%d ", counter ); } while ( ++counter <= 10 ); getch(); }

/* calculate the average of n numbers */ #include <stdio.h> main () { int n, count = 1 ; float x, average, sum = 0; printf ("How many numbers? " ) ; scanf ("%d", &n) ; do { printf ( " x = " ) ; scanf("%f", &x); sum += x; ++count; } while (count <= n); /* calculate the average and display the answer */ average = sum/n; printf ( "\nThe average is %.2f", average) ; getch(); } #include <stdio.h> main() { int digit; clrscr(); for (digit = 0; digit <= 10; ++digit) printf ( "%d " ,digit ); getch(); } #include <stdio.h> main() { int digit = 0; clrscr(); for (; digit <= 10; ) printf ("%d " , digit++ ) ; getch(); }

#include <stdlib.h> void main() { int i; clrscr(); for ( i = 1; i <= 20; i++ ) { printf( "%d ", 1 + ( rand() % 6 ) ); if ( i % 5 == 0 ) printf( "\n" ); } getch(); } /*Randomizing die-rolling program */ #include <stdlib.h> #include <stdio.h> void main() { int i; unsigned seed; clrscr(); printf( "Enter seed: " ); scanf( "%u", &seed ); srand( seed ); for ( i = 1; i <= 20; i++ ) { printf( "%d ", 1 + ( rand() % 6 ) ); if ( i % 5 == 0 ) printf( "\n" ); } getch(); }

/* Roll a six-sided die 6000 times */ #include <stdio.h> #include <stdlib.h> void main() { int face, roll, frequency1 = 0, frequency2 = 0, frequency3 = 0, frequency4 = 0, frequency5 = 0, frequency6 = 0; for ( roll = 1; roll <= 6000; roll++ ) { face = 1 + rand() % 6; switch ( face ) { case 1: ++frequency1; break; case 2: ++frequency2; break; case 3: ++frequency3; break; case 4: ++frequency4; break; case 5: ++frequency5; break; case 6: ++frequency6; break; } } printf( printf( printf( printf( printf( printf( printf( }

"%s%13s\n", "Face", "Frequency" ); " 1%13d\n", frequency1 ); " 2%13d\n", frequency2 ); " 3%13d\n", frequency3 ); " 4%13d\n", frequency4 ); " 5%13d\n", frequency5 ); " 6%13d\n", frequency6 );

/* Program Reversing the digits */ #include <stdio.h> void main() { int number = 0; int rnum = 0; int temp = 0; printf("\nEnter a positive integer: "); scanf("%d", &number); temp = number; do { rnum = 10*rnum + temp % 10; temp = temp/10; } while (temp); printf ("\nThe number %d reversed is

%d \n", number, rnum );

}

/* What does this program print? */ #include <stdio.h> void main( void ) { int count = 1; while ( count <= 10 ) { printf( "%s\n", count % 2 ? "****" : "++++++++" ); count++; } } /* Initializing an array with a initializer list */ #include <stdio.h> void main( void ) { int n[ 10 ] = { 32, 27, 64, 18, 95, 14, 90, 70, 60, 37 }; int i; /* counter */ printf( "%s%13s\n", "Element", "Value" ); for ( i = 0; i < 10; i++ ) { printf( "%7d%13d\n", i, n[ i ] ); }

/* Program Averaging ten numbers - storing the numbers the easy way */ #include <stdio.h> void main() { int numbers[10]; int count = 10; int sum = 0; float average = 0.0f; int i = 0; printf("\nEnter the 10 numbers:\n"); /* Read the ten numbers to be averaged */ for(i = 0; i < count; i ++) { printf("%2d> ",i+1); scanf("%d", &numbers[i]); sum += numbers[i]; } average = (float)sum/count; printf("Average of the ten numbers entered is: %.2f\n", average); } /* Histogram printing program */ #include <stdio.h> #define SIZE 10 void main( void ) { /* use initializer list to initialize array n */ int n[ SIZE ] = { 19, 3, 15, 7, 11, 9, 13, 5, 17, 1 }; int i; /* outer for counter for array elements */ int j; /* inner for counter counts *s in each histogram bar */ printf( "%s%13s%17s\n", "Element", "Value", "Histogram" ); /* for each element of array n, output a bar of the histogram */ for ( i = 0; i < SIZE; i++ ) { printf( "%7d%13d ", i, n[ i ]) ; for ( j = 1; j <= n[ i ]; j++ ) { printf( "%c", '*' ); } printf( "\n" ); }

} /*Creating and using a programmer-defined function */ #include <stdio.h> int square( int y ); void main( void ) { int x; for ( x = 1; x <= 10; x++ ) { printf( "%d ", square( x ) ); } printf( "\n" ); } int square( int y ) { return y * y; }

/* Finding the maximum of three integers */ #include <stdio.h> int maximum( int x, int y, int z ); void main( void ) { int number1; int number2; int number3; printf( "Enter three integers: " ); scanf( "%d%d%d", &number1, &number2, &number3 ); printf( "Maximum is: %d\n", maximum( number1, number2, number3 ) ); } int maximum( int x, int y, int z ) { int max = x; if ( y > max ) { max = y; } if ( z > max ) { max = z; } return max; }

/* A scoping example */ #include <stdio.h> void useLocal( void ); void useStaticLocal( void ); void useGlobal( void ); int x = 1; main( void ) { int x = 5; printf("local x in outer scope of main is %d\n", x ); { int x = 7; printf( "local x in inner scope of main is %d\n", x ); } printf( "local x in outer scope of main is %d\n", x ); useLocal(); useStaticLocal(); useGlobal(); useLocal(); useStaticLocal(); useGlobal(); printf( "\nlocal x in main is %d\n", x ); } void useLocal( void ) { int x = 25; printf( "\nlocal x in useLocal is %d after entering useLocal\n", x ); x++; printf( "local x in useLocal is %d before exiting useLocal\n", x ); }

void useStaticLocal( void ) { /* initialized only first time useStaticLocal is called */ static int x = 50;

printf( "\nlocal static x is %d on entering useStaticLocal\n", x ); x++; printf( "local static x is %d on exiting useStaticLocal\n", x ); } void useGlobal( void ) { printf( "\nglobal x is %d on entering useGlobal\n", x ); x *= 10; printf( "global x is %d on exiting useGlobal\n", x ); }

/*Passing arrays to functions */ #include <stdio.h> #define SIZE 5 void modifyArray( int [], int ); int main() { int a[ SIZE ] = { 0, 1, 2, 3, 4 }, i; for ( i = 0; i < SIZE; i++ ) printf( "%3d", a[ i ] ); printf( "\n" ); modifyArray( a, SIZE ); /* passed call by reference */ printf( "The values of the modified array are:\n" ); for ( i = 0; i < SIZE; i++ ) printf( "%3d", a[ i ] ); return 0; } void modifyArray( int b[], int size ) { int j; for ( j = 0; j <= size - 1; j++ ) b[ j ] *= 2; }

/* Demonstrating the const type qualifier with arrays */ #include <stdio.h> void tryToModifyArray( const int [] ); int main() { int a[] = { 10, 20, 30 }; tryToModifyArray( a ); printf("%d %d %d\n", a[ 0 ], a[ 1 ], a[ 2 ] ); return 0; } void tryToModifyArray( const int b[] ) { b[ 0 ] /= 2; /* error */ b[ 1 ] /= 2; /* error */ b[ 2 ] /= 2; /* error */ }

/* Initializing multidimensional arrays */ #include <stdio.h> void printArray( const int [][ 3 ] ); int main() { int array1[ 2 ][ 3 ] = { { 1, 2, 3 }, { 4, 5, 6 } }, array2[ 2 ][ 3 ] = { 1, 2, 3, 4, 5 }, array3[ 2 ][ 3 ] = { { 1, 2 }, { 4 } }; printf( "Values in array1 by row are:\n" ); printArray( array1 ); printf( "Values in array2 by row are:\n" ); printArray( array2 ); printf( "Values in array3 by row are:\n" ); printArray( array3 ); return 0; } void printArray( const int a[][ 3 ] ) { int i, j; for ( i = 0; i <= 1; i++ ) { for ( j = 0; j <= 2; j++ ) printf( "%d ", a[ i ][ j ] ); printf( "\n" ); } }

/* Recursive factorial function */ #include <stdio.h> long factorial( long number ); void main( void ) { int i; for ( i = 0; i <= 10; i++ ) { printf( "%2d! = %ld\n", i, factorial( i ) ); }

} long factorial( long number ) { if ( number <= 1 ) { return 1; } else { return ( number * factorial( number - 1 ) ); } }

/* Program Displaying a string */ #include <stdio.h> void main() { printf("The character \0 is used to terminate a string"); } /* Program Lengths of strings */ #include <stdio.h> void main() { char str1[40] = "To be or not to be"; int count = 0; while (str1[count] != '\0') count++; printf("\nThe length of the string %s is %d characters.", str1, count); }

/* Program Joining strings */ #include <stdio.h> void main() { char str1[40] = "To be or not to be"; char str2[40] = ",that is the question"; int count1 = 0; int count2 = 0; while (str1[count1] != '\0') count1++; while (str2[count2] != '\0') count2++; /* Check that we have enough space for both strings if(sizeof str1 < count1 + count2 + 1) printf("\length is small"); else { count2 = 0; while(str2[count2] != '\0') str1[count1++] = str2[count2++];

*/

str1[count1] = '\0'; printf("\n%s\n", str1 ); } }

/* Program Joining strings - revitalised */ #include <stdio.h> #include <string.h> #define STR_LENGTH 40 void main() { char str1[STR_LENGTH] = "To be or not to be"; char str2[STR_LENGTH] = ",that is the question"; if(STR_LENGTH

>

strlen(str1)

+

strlen(str2))

*/ printf("\n%s\n", strcat(str1, str2) ); else printf("\n can't combine"); }

/*

Enough

space

?

/* Program Testing characters in a string */ #include <stdio.h> #include void main() { char buffer[80]; int i = 0; int num_letters = 0; int num_digits = 0; printf("\nEnter characters:\n"); gets(buffer);

an

interesting

string

of

less

/* Read a string into buffer

than */

while(buffer[i] != '\0') { if(isalpha(buffer[i])) num_letters++; /* Increment letter count */ if(isdigit(buffer[i])) num_digits++; /* Increment digit count */ i++; } printf("\nYour string contained %d letters and %d digits.\n", num_letters, num_digits); }

80

/* Program Arrays of strings */ #include <stdio.h> void main() { char str[][40] = { "To be or not to be" , ",that is the question" }; int count1 = 0; /* Length of first string */ int count2 = 0; /* Length of second string */ /* find the length of the first string */ while (str[0][count1] != '\0') count1++; /* Find the length of the second string */ while (str[1][count2] != '\0') count2++; /* Check that we have enough space for both strings if (sizeof str[0] < count1 + count2 + 1) printf("\n can't combine"); else

*/

{ /* Copy 2nd string to first */ count2 = 0; while ((str[0][count1++] = str[1][count2++]) != '\0'); printf("\n%s", str[0]); } }

/* Output combined string */

/* Comparing strings #include <stdio.h> #include <string.h>

*/

void main() { char word1[20]; char word2[20]; printf("\nType in the first word:\n1: "); scanf("%s", word1); printf("Type in the second word:\n 2: "); scanf("%s", word2); /* Compare the two words */ if(strcmp(word1,word2) == 0) printf("You have entered identical words"); else printf("%s comes before %s", (strcmp(word1, word2) < 0) ? word1 : word2, (strcmp(word1, word2) < 0) ? word2 : word1); }