len( ) vs count( ) | Python String

Python String method len( ) is used to get the length of the given string.

name = "Welcome to techies sphere"

print(len(name))

Output: 25 

 

Python String method count( ) is used to get the number of occurrences of a substring in the given string.

string = "Welcome to techies sphere."

subString = "to"

print(string.count(subString)) 

Output: 1

 

Syntax of count( ) method:

string.count( subString, start, end )

 

Parameters:

subString - string whose count is to be found. 

start (Optional) - starting index within the string where count starts. 

end (Optional) - ending index within the string where count ends.

string = "Welcome to techies sphere, to learn and grow."

subString = "to"

print(string.count(subString, 5, 30))

Output: 1

Recursion in C

Recursion is a process in which a function calls itself. In a programming language, if a program allows calling of a function inside the same function, then the function is termed as recursive function and this  process of calling itself is called Recursion.

There are two main requirements for a function to be recursive:

1. Terminating condition -  the function must return when the terminating condition is satisfied.

2. Recursive call - the function must call itself.

Example:-

int fun()

{

    ...

    ...

    fun();

    ...

    ...

}

Here we can see that, the function fun( ) calls itself.

 

C program:-

C program to calculate the the sum of the ‘nth’ number using recursion.

 

#include <stdio.h>

 

int fun(int n)

{

    if (n == 0)

        return 0;

    else

        return fun(n - 1) + n;

}

int main()

{

    int sum = 0, x;

    printf("number");

    scanf("%d", &x);

    sum = fun(x);

    printf("%d\n", sum);

    return 0;

}

Sum of two number without using '+' operator

 

Idea 1:-

Half adder logic

A half adder has two inputs for the two bits to be added and two outputs one from the ‘sum’ and the other from the ‘carry’ into the higher adder position. A circuit is called a carrying  signal from the addition of the sum of the less significant bits from the X-OR gate the out from AND gate.

Truth table :-

A	B	SUM	CARRY
0	0	0	0
0	1	1	0
1	0	1	0
1	1	0	1

 

In the truth table.  you can see I have provided all possible combinations of  A and B. Now if you observe the truth table clearly,  the sum is nothing but A X-or  B. As we know in X-or two different bits give the output  1.

Carry is equal to A and B because we have like 1, 1 input combination the output is equal to one. Therefor

SUM = A  XOR  B

Carry = A  AND  B

C program

#include <stdio.h>

 

int main()

{

    int a, b, sum, carry;

    printf("a=");

    scanf("%d", &a);

    printf("b=");

    scanf("%d", &b);

 

    while (b != 0)

    {

        sum = a ^ b;

        carry = (a & b) << 1;

        a = sum;

        b = carry;

    }

    printf("sum = %d", sum);

    return 0;

}

Explanation of program

Step 1:  Declared two integer type variable a and b. sum and carry taken from to logic gate which is XOR and AND.

Step 2: Give the input in an integer type variable ‘a’ and ‘b’ by scanf() function.

Step 3: Use while loop check b is not equal to zero. the sum is equal to a^b then after carry is equal to a&b <<1 . and stored the value of sum in a. and stored the value of carry in b.

Step 4: Print the sum.

Output:-

Idea 2

Using while loop

C program

#include <stdio.h>

 

int main()

{

    int a, b;

    printf("a=");

    scanf("%d", &a);

    printf("b=");

    scanf("%d", &b);

 

    if (b > 0)

    {

        while (b != 0)

        {

            a++;

            b--;

        }

    }

    else if (b < 0)

    {

        while (b != 0)

        {

            a--;

            b++;

        }

    }

 

    printf("sum = %d\n", a);

    return 0;

}

Output:-

While loop in c

A while loop allows a part of the code to be executed multiple times depending upon a given Boolean condition. it called a pre-tested loop. Then the ‘While loop’ is mostly used in the case where the number of repetitions is no known in advance.

Syntax of while loop:-

          While(condition)

          {

               Statement;

               Increament/decreasement;

          }

Flowchart:-

Example:-

Problem 1

Write a C program to calculate the sum of two numbers without using the plus operator.

Algorithm

Step 1   a++;  b--;

Step 2   Repeat Step 1 until b becomes 0

Program of the above problem

#include <stdio.h>

 

int main()

{

    int a, b;

    printf("a=");

    scanf("%d", &a);

    printf("b=");

    scanf("%d", &b);

 

    while (b != 0)

    {

        a++;

        b--;

    }

    printf("sum = %d\n", a);

    return 0;

}

Output:-

Note:  This logic is design for only positive integers.

Problem 2

Write a C program to the counting of the number 1 to 10 using a while loop.

#include<stdio.h>

 

int main()

{

    int i=1;

 

    while(i<=10)

    {

        printf("%d\n", i);

        i++;

    }

    return 0;

 

}

Output:-

Problem 3

Write a C program to print the 2s table using a while loop.

#include <stdio.h>

 

int main()

{

    int a, n, i;

    printf("number");

    scanf("%d", &n);

    (i = 1);

    while (i<=n)

    {

        a = 2 * i;

        {

            printf("%d\n", a);

        }

        i++;

    }

}

Output:-

Some basic C programs using Conditional Operator

Conditional operator simply returns one value when the condition is true and returns another value if the condition is false. It also knows as a ternary operator.

Syntax of a ternary operator

  (condition) ? Expression: Expression;

Example

(a>0)?1:0; evaluates to true so 1.

Now understand the ternary operator with the help of some basic problem.

Problem 1

Write a C program to check the numbers are positive or negative.

#include <stdio.h>

 

int main()

{

    int a, c;

    printf("Enter the number ");

    scanf("%d", &a);

    c = (a>0) ? printf("positive number ") : printf("Negative number ");

    // (a > 0) ? printf("positive number") : printf("Negative number");

}

Understanding the above code:

    Declared two integer type variables which are a and c.

    Input is taken in variable ‘a’ by  ‘scanf( )’ function.

    Integer type variable c is used to store the decision based upon the condition by the compiler.

Output

Using this in the above code

 (a > 0) ? printf("positive number") : printf("Negative number");

With both the code output is similar. 

Problem 2

Write a C program to determine the greatest number between the three numbers.

#include <stdio.h>

 

int main()

{

    int a, b, c, big;

    printf("a=");

    scanf("%d", &a);

    printf("b=");

    scanf("%d", &b);

    printf("c=");

    scanf("%d", &c);

    big = a > b ? (a > c ? a : c) : (b > c ? b : c);

    printf("Greatest number %d\n", big);

}

Output

Conditional Operator in C

Conditional operator is a Ternary operator available in list of operators in the C language. It requires three operands. Conditional statements are used to make decision based upon condition. Ternary operator requires two special symbols (‘?’ and ‘:’) to express it.

The program execution of conditional operator is just like if-else conditional statement.

Syntax of conditional operator

Expression 1? Expression 2: Expression 3;

Working of Ternary Operator

As in Expression 1? Expression 2:  Expression3. Expression 1 is the Boolean expression. If Expression1 evaluates to 0 which is a Boolean expression then that simply means FALSE and if the Expression1 evaluates to 1 this simply means TRUE therefore Expression3 or Expression2 will get evaluated based on Expression1.

For example

#include<stdio.h>

int main ()

{

    int a, c;

    printf("Enter the number  ");

    scanf("%d", &a);

    c = (a>5) ? printf("True") : printf("False");

}

Output:

String Format in Python

Formatting string enables the capability to add dynamic content or string to it in an easy way. It allows to update contents in a string in simpler way.

String Format using format () method

Syntax: template_string.format(positional_args, keyword_args) 

The template string contains the replacement fields which can be replaced using the positional_args and keyword_args used in the method. The method returns the formatted string.

In the template string, the replacements fields are enclosed within curly braces “{  }”. Rest of the string content remains unchanged.

Using positional arguments

print('{0} {1} the {2} nicely'.format('This', 'formats', 'string'))

 

Here, <template_string> is '{0} {1} the {2} nicely'. The replacement fields are {0}, {1}, and {2} with zero-based positional arguments 'This', 'formats', 'string'. The replacements fields are replaced with the corresponding positional arguments by the format method.

 

Using keyword arguments

print('{name} is {age} years old'.format(name='Python', age= 30))

 

Here, the replacement fields are {name}, {age}and the corresponding keyword arguments with values. Each fields are replaced with corresponding keyword argument values.