How Nested for loop worked

Question

r=0
for x in range(10):
for y in range(5):
r+=1
print(r)

What's the output???
And how ????

Answer 1

the output is 50

My reason is because 10 x 5 = 50

Lets think about how a for loop behaves.

a for loop needs to finish all the set of instructions inside it to finish a iteration.

therefore the program will execute and perform the the x for loop.

once it performs the x for loop it needs to finish the 5 iterations of the y for loop to finish one iteration of the x for loop.

another example of nested for loop

r=0;
for x in range(10):
for y in range(5):
for z in range(20):
r+=1;
print(r);

the answer here is 1000 because 10 x 5 x 20 = 1000.

Answer 2

your outer loop execute 10 time and inside loop will execute total 5 time r+=1 will work as a counter
if your outer loop work one times then inside loop will work 5 times like this

initial outer loop x=0
Jump to inside
y=0 this inside loop will execute 5 time first time
r+=1=1 then again y=1
r+=1 means r=1+1 again y will increase by 1 so y=2
r=2+1
Same for y=3
r=3+1
.....
when y will be 5 here condition false and outer loop will be execute at this time x will will be increase by one initial it was 0 .
Now 1 again inside loop work 5 time
When x =2 again inside loop work 5 time
x=3. Again 5 times

.....
When
x=10 here condition false