Question on C programming lanuage

Question

Why 'count' variable value doesn't set to 0 on every call to 'incr' function?

Comments

All(Local or Global) Static variable life time throughout the program but Local static variable scope in the define function and Global variable throughout the program.
(*******) All static variable initialize with zero by default
(*******) All Global variable initialize with zero by default

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Here the count is static variable and its value is zero and as we know that scope of static variable is throughout the program.

when i=0 function incr(0) is called 

count =count+i => 0+0 =0

when i=1 function incr(1) is called 

count =count+i => 0+1 =1

when i=2 function incr(2) is called 

count =count+i => 1+2 =3

when i=3 function incr(3) is called 

count =count+i => 3+3 =6

when i=4 function incr(4) is called 

count =count+i => 6+4 =10

when i=5 function incr(5) is called 

count =count+i => 10+5 =15

when i=6 loop terminates

 ANSWER IS COUNT = 15

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Isnt the count value set to 0 on each function call. If it is set to zero on each call. The value of j should b 5 at the end of program.

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      No, the count is a static variable.

      when you write static int x = 0;

       this line executes once and always x takes the latest value.

---->Static variable initialized only once.

see https://www.geeksforgeeks.org/static-variables-in-c/

Answer 1

here static int count= 0 means memory create for count for compile time only ..ans will be 15 only

at cal(0)= 0

at cal(1)= 1

at cal(2)=3

at cal(3)= 6

at cal(4)= 10

at cal(5)=15

What ur talking about constant int count= 0. 

Answer 2

Count is a static variable which allocates its memory in data segment unlike the usual stack . Therefore when a function is called again the value still remains stored and it refers to the old location in data segment every time. Had count been a local variable (int count =0 )it would be stored in stack and then every time function is called count would be allocated different memory locations in stack since the activation records are different for each call of the function. Then what you asked would have been true and j value would be 5.

Comments

Is the statement containing the declaration of static variable will be skipped after the first function call?

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i will be like that when static come next time then it will tell memory created already at compile time so dnt creat now.

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@sv_jan5 yes you can think it as if it is skipped but the reality is it is pointing to same memory location every time.

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ok now its clear.

Answer 3

15

Because static variables initialize only on time.