C Tutorial/Array/Array Search
Binary search of an array
<source lang="cpp">#include <stdio.h>
- define SIZE 15
int binarySearch( const int b[], int searchKey, int low, int high ); int main() {
int a[ SIZE ];
int i;
int key = 10;
int result = -1;
for ( i = 0; i < SIZE; i++ ) {
a[ i ] = 2 * i;
}
result = binarySearch( a, key, 0, SIZE - 1 );
if ( result != -1 ) {
printf( "\n%d found in array element %d\n", key, result );
} else {
printf( "\n%d not found\n", key );
}
return 0;
} int binarySearch( const int b[], int searchKey, int low, int high ) {
int middle;
while ( low <= high ) {
middle = ( low + high ) / 2;
if ( searchKey == b[ middle ] ) {
return middle;
} else if ( searchKey < b[ middle ] ) {
high = middle - 1;
} else {
low = middle + 1;
}
}
return -1;
}</source>
10 found in array element 5
Linear search of an array
<source lang="cpp">#include <stdio.h>
- define SIZE 100
int linearSearch( const int array[], int key, int size ); int main() {
int a[ SIZE ];
int x;
int searchKey;
int element;
for ( x = 0; x < SIZE; x++ ) {
a[ x ] = 2 * x;
}
printf( "Enter integer search key:\n" );
scanf( "%d", &searchKey );
element = linearSearch( a, searchKey, SIZE );
if ( element != -1 ) {
printf( "Found value in element %d\n", element );
}
else {
printf( "Value not found\n" );
}
return 0;
} int linearSearch( const int array[], int key, int size ) {
int n;
for ( n = 0; n < size; ++n ) {
if ( array[ n ] == key ) {
return n;
}
}
return -1;
}</source>
Enter integer search key: 2 Found value in element 1
