Lecture 2: Write Your First Program in C++
This is the 2nd lecture of our DSA series. We will see how a program runs and what does
each line mean in this lecture. This is how the compilation process work So it is compiler
which makes it possible for us to run a source code. Coding Ninjas has supported us in
providing this amazing DSA course to you. Courses are available in both Hindi and
English. you need an IDE to write, run and execute a code. There are ma ny IDEs out there -
CodeBlocks, VsCode and many more - which you do n't even need to install Replit is one
of them. You can directly create a C++ there and run it using Replit. In C++, many
namespaces are there which have cout functions in them so if we wa nt to use cout , we
have to add this file to our code. We use these signs to output the result into standard
namespace. If you will use > > by mistake by mistake, then it will give you compilation
error So we use this operator to display output.
We are going to talk about data types and variables. Whenever you have to story any
information or data in the memory. You have to mention what type of data it is and how
much memory it will take. For eg- int a = 5, a is a variable in memory which is of int type
and it has value 5 in it. We have certain rules which we have to follow when we are giving
names. There is a function named sizeof , which will tell you about the space being used by
any variable. In memory, first 29 bits will have 0, and last 3 bits will be 101, so in memory
the first 29 bit will have 0 and the last 3bits will have 101. We have a way to story multiple
characters but we will see that in upcoming lectures. In c++, all the characters are mapped
to some ASCII value in memory. We will just store binary form of ASCII value of any
character. If we have 4 different bytes with some binary value, how will compiler know
whether it is a single Int value of 4 separate char values ? Compiler will come to know
from data types which we used when we declared any variable. This process of converting
one data type into another is known as type casting.
There are few steps which I have to follow while storing a negative number. Let 's say the
number is -5 1st - Ignore the negative sign 2nd - Convert into binary representation = 101
3rd - Take 2 's complement and store it Now we can store negative numbers simply too, by
just using their first bit as their sign. With this our maximum value will be limited to 2^31 -
1 instead of 2^32 -1. 2/5 will give 0 and not 0. 4 , why ? because you are storing your
answer in a int variable. To get answer in float, store it in a float variable. If you want to
check whether A is equal to B or not I can do that using this ( a==b ) relational operators =
, > , < , ! = is an assignment operator, because we are assigning 3 to a. logical operators
have & & and & is used to check multiple conditions. We have got the basic idea of
operators. We know what things to keep in mind while dividing , how to store negative
numbers & & operators and ! operators. Now let 's move ahead towards bitwise operators I
will teach these when we will use them in upcoming sessions. We will do Bitwise operators
later.
This is the 2nd lecture of our DSA series. We will see how a program runs and what does
each line mean in this lecture. This is how the compilation process work So it is compiler
which makes it possible for us to run a source code. Coding Ninjas has supported us in
providing this amazing DSA course to you. Courses are available in both Hindi and
English. you need an IDE to write, run and execute a code. There are ma ny IDEs out there -
CodeBlocks, VsCode and many more - which you do n't even need to install Replit is one
of them. You can directly create a C++ there and run it using Replit. In C++, many
namespaces are there which have cout functions in them so if we wa nt to use cout , we
have to add this file to our code. We use these signs to output the result into standard
namespace. If you will use > > by mistake by mistake, then it will give you compilation
error So we use this operator to display output.
We are going to talk about data types and variables. Whenever you have to story any
information or data in the memory. You have to mention what type of data it is and how
much memory it will take. For eg- int a = 5, a is a variable in memory which is of int type
and it has value 5 in it. We have certain rules which we have to follow when we are giving
names. There is a function named sizeof , which will tell you about the space being used by
any variable. In memory, first 29 bits will have 0, and last 3 bits will be 101, so in memory
the first 29 bit will have 0 and the last 3bits will have 101. We have a way to story multiple
characters but we will see that in upcoming lectures. In c++, all the characters are mapped
to some ASCII value in memory. We will just store binary form of ASCII value of any
character. If we have 4 different bytes with some binary value, how will compiler know
whether it is a single Int value of 4 separate char values ? Compiler will come to know
from data types which we used when we declared any variable. This process of converting
one data type into another is known as type casting.
There are few steps which I have to follow while storing a negative number. Let 's say the
number is -5 1st - Ignore the negative sign 2nd - Convert into binary representation = 101
3rd - Take 2 's complement and store it Now we can store negative numbers simply too, by
just using their first bit as their sign. With this our maximum value will be limited to 2^31 -
1 instead of 2^32 -1. 2/5 will give 0 and not 0. 4 , why ? because you are storing your
answer in a int variable. To get answer in float, store it in a float variable. If you want to
check whether A is equal to B or not I can do that using this ( a==b ) relational operators =
, > , < , ! = is an assignment operator, because we are assigning 3 to a. logical operators
have & & and & is used to check multiple conditions. We have got the basic idea of
operators. We know what things to keep in mind while dividing , how to store negative
numbers & & operators and ! operators. Now let 's move ahead towards bitwise operators I
will teach these when we will use them in upcoming sessions. We will do Bitwise operators
later.
