HIGH LEVEL LANGUAGES:

During 1960s computers started to gain popularity and it became necessary to develop
languages that were more like natural languages such as English so that a common user could
use the computer efficiently. Since assembly language required deep knowledge of computer
architecture, it demanded programming as well as hardware skills to use computers. Due to
computer’s widespread usage, early 1960s saw the emergence of the third generations
programming languages (3GL). Languages such as COBOL, FORTRAN, BASIC, and C are
examples of 3GLs and are considered high-level languages.
High level languages are similar to English language. Programs written using these
languages can be machine independent. A single high-level statement can substitute several
instructions in machine or assembly language. Unlike assembly and machine programs, highlevel
programs may be used with different types of computers with little or no modification, thus
reducing the re-programming time.
In high-level language, programs are written in a sequence of statements to solve a
problem. For example, the following BASIC code snippet will calculate the sum of two numbers
LET X = 10
LET Y = 20
LET SUM = X + Y PRINT SUM
The first two statements store 10 in variable X (memory locations name) and 20 in
variable, Y, respectively. The third statement again creates a variable named SUM, which will
store the summation of X and Y value. Finally, the output is printed, that is, the value stored in
SUM is printed on the screen.