The evolution of programming languages

on

WHAT IS PROGRAMMING ?

Programming, also known as coding, is the process of giving instructions to a computer to perform specific tasks by writing code in a programming language. It involves designing and implementing algorithms, which are step-by-step procedures, to solve problems. 


Programming

• it's hard to do the programming to get something done

• details are hard to get right, very complicated, finicky

 • not enough skilled people to do what is needed

• therefore, enlist machines to do some of the work – leads to programming languages

• it's hard to manage the resources of the computer

• hard to control sequences of operations

 • in ancient times, high cost of having machine be idle

• therefore, enlist machines to do some of the work – leads to operating systems

Evolution of programming languages 

• 1940's: machine level – use binary or equivalent notations for actual numeric values 

• 1950's: "assembly language" – names for instructions: ADD instead of 0110101, etc. – names for locations: assembler keeps track of where things are in memory; translates this more humane language into machine language – this is the level used in the "toy" machine – needs total rewrite if moved to a different kind of CPU 

loop get # read a number 

if zero done # no more input if number is zero 

add sum # add in accumulated sum

 store sum # store new value back in sum

 go to loop # read another number 

done load sum # print sum 

print 

stop sum 0 # sum will be 0 when program starts

Evolution of programming languages 1960's 

• "high level" languages -- Fortran, Cobol, Basic – write in a more natural notation, e.g., mathematical formulas – a program ("compiler", "translator") converts into assembler – potential disadvantage: lower efficiency in use of machine – enormous advantages: accessible to much wider population of users portable: same program can be translated for different machines more efficient in programmer time

sum = 0

 10 read(5,*) num

 if (num .eq. 0) goto 20 

sum = sum + num 

goto 10 20 write(6,*) sum 

stop 

end

Evolution of programming languages 1970's 

• "system programming" languages -- C – efficient and expressive enough to take on any programming task writing assemblers, compilers, operating systems – a program ("compiler", "translator") converts into assembler – enormous advantages: accessible to much wider population of programmers portable: same program can be translated for different machines faster, cheaper hardware helps make this happen

#include<stdio.h>

int main() 

{

 int num, sum = 0; 

while (scanf("%d", &num) != -1 && num != 0)

 sum += num;

 printf("%d\n", sum); 

}

C code compiled to assembly language (SPARC):

#include<stdio.h>

 Int main()

 {

 int num, sum = 0;

while (scanf("%d", &num) != -1

&& num != 0)

sum = sum + num;

printf("%d\n", sum);

 }

C code compiled to assembly language:


#include<stdio.h>
 
int  main() 
{ 

int num, sum = 0; 

while (scanf("%d", &num) != -1 
&& num != 0)

 sum = sum + num; 

printf("%d\n", sum); 

}

Evolution of programming languages 1980's :

• "object-oriented" languages: C++ – better control of structure of really large programs better internal checks, organization, safety – a program ("compiler", "translator") converts into assembler or C – enormous adzvantages: portable: same program can be translated for different machines faster, cheaper hardware helps make this happen

#include<stdio.h>

int main() 

{

 int num, sum = 0;

 while (cin >> num && num != 0) sum += num; 

cout << sum << endl;

 }

Evolution of programming languages, 1990's :

• "scripting", Web, component-based, : Java, Perl, Python, Visual Basic, Javascript,  – write big programs by combining components already written – often based on "virtual machine": simulated, like fancier toy computer – enormous advantages: portable: same program can be translated for different machines faster, cheaper hardware helps make this happen

var sum = 0, num; // javascript 

num = prompt("Enter new value, or 0 to end") 

while (num != 0)

 { 

sum = sum + parseInt(num)

 num = prompt("Enter new value, or 0 to end") 

}

 alert("Sum = " + sum)

Evolution of programming languages, 2000's :

• so far, more of the same – more specialized languages for specific application areas Flash/Action script for animation in web pages – ongoing refinements / evolution of existing languages C, C++, Fortran, Cobol all have new standards in last few years 

• copycat languages – Microsoft C# strongly related to Java – scripting languages similar to Perl, Python, et al 

• better tools for creating programs without as much programming – mixing and matching components from multiple languages

Why so many programming languages ?

• every language is a tradeoff among competing pressures – reaction to perceived failings of others; personal taste 

• notation is important – "Language shapes the way we think and determines what we can think about." Benjamin Whorf – the more natural and close to the problem domain, the easier it is to get the machine to do what you want 

• higher-level languages hide differences between machines and between operating systems 

• we can define idealized "machines" or capabilities and have a program simulate them -- "virtual machines" – programming languages are another example of Turing equivalence