1. Array
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14. Contd.
For example, the array marks can be initialized while declaring using this statement.
                                  int marks[5]={51,62,43,74,55};
The elements of the array marks can be referred to as marks [0], marks [1],marks [2], marks [3] and marks [4], respectively.
The memory representation of the array marks is shown in Figure. As each element is of the type int (that is, 2 bytes long), the array marks occupies ten contiguous bytes in memory and these bytes are reserved in the memory at the compile-time.
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15. Problem double percentage[50];
If this array percentage is stored in memory starting from address then what will be the address of percentage[20] element.
Ans: *8= 3160
What will be size of array?
Ans:400
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17. Example 1: Find the minimum of a set of 10 numbers
#include <stdio.h> main(){ int a[10], i, min; printf(“Enter 10 numbers:”); for (i=0; i<10; i++) scanf (“%d”, &a[i]); min = a[0]; for (i=1; i<10; i++){ if (a[i] < min) min = a[i]; } printf (“\n Minimum is %d”, min);
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18. Alternate Version1 for last problem
#include <stdio.h>
#define SIZE 10
main(){
int a[SIZE], i, min;
printf(“Enter 10 numbers:”);
for (i=0; i< SIZE; i++)
scanf (“%d”, &a[i]);
min = a[0];
for (i=1; i< SIZE; i++){
if (a[i] < min)
min = a[i]; }
printf (“\n Minimum is %d”, min);
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19. Alternate Version2 for last problem
#include <stdio.h>
main(){
int a[500], i, min;
printf(“Enter number of elements:”);
scanf(“%d”,&n);
printf(“Enter n numbers:”);
for (i=0; i< n; i++)
scanf (“%d”, &a[i]);
min = a[0];
for (i=1; i< n; i++){
if (a[i] < min)
min = a[i]; }
printf (“\n Minimum is %d”, min);
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20. Things you can not do with array
You cannot use = to assign one array variable to another
E.g. a = b; is illegal where a and b are arrays.
You cannot use == to directly compare array variables
e.g. if (a = = b) is illegal.
You cannot use directly scanf or printf arrays
printf (“…….”, a); is illegal.
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21. How to copy the elements of one array to another?
By copying individual elements
for (j=0; j<25; j++)
a[j] = b[j];
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22. How to read the elements of an array?
By reading them one element at a time
for (j=0; j<25; j++)
scanf (“%f”, &a[j]);
The ampersand (&) is necessary.
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24. Problem- linear search in one-D array
Write a program that asks the user to enter n integers of an array and an integer x. The program must search if n is in the array of n integers.
Following is the sample output
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25. void main() { int array[100], search, c, n;
printf("Enter the number of elements in array\n"); scanf("%d",&n);  
printf("Enter %d integer(s)\n", n);  
for (c = 0; c < n; c++)
scanf("%d", &array[c]);  
printf("Enter the number to search\n");
scanf("%d", &search);  
for (c = 0; c < n; c++) {
if (array[c] == search){ /* if required element found */
printf("%d is present at location %d.\n", search, c+1);
break; }
if (c == n)
printf("%d is not present in array.\n", search);  
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26. Sort one-D array and find its median
void main(){ int i,j,n,temp,arr[100]; printf(“Enter n:”); for(i=0;i<n;i++) scanf(“%d”,&arr[i]); for(i=0; i<n-1; i++) { for(j=i+1; j<n; j++) { if(arr[i] > arr[j]) { // swap elements temp = arr[i]; arr[i] = arr[j]; arr[j] = temp; } if(n%2==0) // if there is an even number of elements, median will be mean of the two elements in the middle printf(“median is=%d”,(x[n/2] + x[n/2 - 1]) / 2.0); else //else return the element in the middle printf(“median is=%d”,x[n/2]);

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30. Initialization of Two-Dimensional Array
Like a single-dimensional array, a two-dimensional array can also be declared and initialized at the same time.
To understand the concept of two-dimensional array initialization, consider this statement. 
int a[3] [2]={
                     {101,51},
         {l02,67},
                     {l03,76} }
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31. Initialization of Two-Dimensional Array
In last statement, an array of type int having three rows and two columns is declared and initialized.
This type of initialization is generally used to increase the readability.
However, the array a can also be initialized using this statement.
  int a[] [2]={101,51,l02,67,l03,76};
In this statement, the first two elements are stored in the first row, next two in the second row and so on.
Note that while initializing a two-dimensional array, mentioning the row size is optional, however, the column size must be specified.
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33. How to read the elements of a 2-D array?
• By reading them one element at a time for (i=0; i<nrow; i++) for (j=0; j<ncol; j++) scanf (“%f”, &a[i][j]); • The ampersand (&) is necessary.
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37. int a[] [2]={101,51,l02,67,l03,76};
For example, the elements of array are referred to as a [0] [0], a [0] [1], a [1] [0], a [1] [1], a [2] [0] and a [2] [1] respectively.
Generally, two-dimensional arrays are represented with the help of a matrix.
However, in actual implementation, two-dimensional arrays are always allocated contiguous blocks of memory.
Figure shows the matrix and memory representation of two-dimensional array a.
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38. Problem long double array[10][15];
If base address is 2000 then what will be the address of
Array[5][6] element;
Ans: 2000+(5*15+6)*10=2810
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39. C program to find average marks obtained by a class of 30 students in a test.
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41. Example: Matrix Addition
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42. Example: Matrix Addition
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43. Indenting C Programs 
Why Indentation is Important: Good style is about making your program
Clear
Understandable and
Easily modifiable. 
Use proper comment in program for better readability.
There are so many Indenting Styles like Kernel style, K&R style and ANSI Style.
We will follow ANSI Style(also known as Allman style).
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44. Rules of ANSI Style 
This style puts the brace associated with a control statement(if,while,for, etc.) on the next line, indented to the same level as the control statement.
Statements within the braces are indented to the next level(indented by one tab).
Following is the code segment without proper indentation
while (x == y) {
printf(“x and y are same”);
printf(“Next What to Do!”); }
Same code segment in ANSI style would be
while (x == y) {
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45. Some Examples of Bad vs Good coding style
Code without proper indentation: void main(){ int a=40000,b=20000; if(a<b) printf(“Wow!”); else printf(“Really!”); } Same code segment in ANSI style would be void main() { if(a<b) // comparison of a and b printf(“Wow!”); else printf(“Really!”);
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46. Some Examples of Bad vs Good coding style
Code without proper indentation: #include<stdio.h> void main(){ int row,col; for (row=1; row<=5; row++) { for (col=1; col<=5; col++) { if(row==1 || row==5 || col==1 || col==5) printf("*"); else printf(" "); } printf("\n");
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47. Some Examples of Bad vs Good coding style
Same code segment in ANSI style would be: void main() { int row,col; for (row=1; row<=5; row++) //outer Loop for (col=1; col<=5; col++) //Inner Loop if(row==1 || row==5 || col==1 || col==5) printf("*"); else printf(" "); } printf("\n");
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48. O/P?
main() { int arr[]=(12,13,14,15,16}; printf(“\n%d , %d”,sizeof(arr), sizeof(arr[0])); } O/p
10,2
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49. O/P?
main() { float a[]= { 12.4, 2.3, 4.5, 6.7}; printf(“\n %d”, sizeof(a)/sizeof(a[0])); } O/p
16/4=4
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50. O/p?
main( ) { int three[3][ ] = { 2, 4, 3, 6, 8, 2, 2, 3 ,1 } ; printf ( "\n%d", three[1][1] ) ; }
Syntax error
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51. Homework Multiply two matrices of orders m*n and n*p respectively.
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