Question

I making a program in which a single line of input containing an integer, print a triangle of asterisks of that size. But my program is not working like this. So can you please have a look on my code and can determine my mistake please. Thanks

line = int(raw_input("Number of lines: "))
a = line * '*'
print a

This is the output I want to produce:

Number of lines: 5
*
**
***
****
*****

Answer 1

Since this is self-education rather than actual classwork, it’s best explained with code and a detailed explanation of what you were doing wrong.

You’re mostly there, in that you have the input and the means by which you can output a certain number of asterisks. Your problem is that you’re only printing one line with the maximum number of asterisks.

You need to loop from 1 up to that number, each time outputting that same kind of line with an increasing length, something like:

line = int (raw_input ("Number of lines: "))
for i in range (1, line + 1):
    print i * '*'

With this code (entering 5), you basically loop with the variable i containing in sequence {1, 2, 3, 4, 5} (range is inclusive at the low end and exclusive at the high end, hence the line + 1).

Within that loop, you output that number of asterisks, giving you your triangle shape:

pax> python testprog.py
Number of lines: 5
*
**
***
****
*****