# Algo: Linear Search

code:

```/*
Count Frequency in an Array(Optimized Version)
Syed Ahmed Zaki -- 2017
*/
#include<stdio.h>
int linear_search(int A[],int n,int x)
{
int i;
for(i=0; i<n; i++)
if(A[i]==x)
return i;
return -1;
}

int main()
{
int x;
int A[]= {5,6,7,8,9};
printf("Put value to search from an array:\n");
scanf("%d",&x);
int out=linear_search(A,5,x);
if(out==-1)
{
}
else
{
printf("%d is in index %d\n",x,out);
}
return 0;

}```

Another Code By Me:

```/*
Count Frequency in an Array(Optimized Version)
Syed Ahmed Zaki -- 2017
*/
#include<stdio.h>
int linear_search(int *A,int n,int x) //*A is passing the value of the array address index
{
int i;
for(i=0; i<n; i++)
if(A[i]==x)
return i;
return -1;
}

int main()
{
int x,i,n;
printf("Array Size:");
scanf("%d",&n);
int A[10005];
for(i=0;i<n;i++)
{
scanf("%d",&A[i]);
}
printf("Put value to search from an array:\n");
scanf("%d",&x);
int out=linear_search(A,5,x);
if(out==-1)
{
}
else
{
printf("%d is in index %d\n",x,out);
}
return 0;

}```

Complexity:
Best Case: O(1)
Worst Case: O(n)
Average Case: O(n/2)=O(n)
Source: http://quiz.geeksforgeeks.org/linear-search/

Pseudocode Looks Like this:

```SEARCH(A, v):
for i = 1 to A.length
if A[i] == v
return i
return NIL```

Another Good Pseudocode:

```LinearSearch(A,n,item)
Begin
for i=0 to n-1 by 1 do
if A[i]==item then
return i;
end if
end for
return -1
End```

Source:

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Author: zakilive