Python usage of format --version2 of Python

[tree123]

    url = 'https://www.qiushibaike.com/pic/page/%d/?s=5184961'
    for pageNum in range(1,3):
        new_url = format(url%pageNum)

Hello,

The quoted code is from a tutorial. And I am learning by myself. The purpose of the lines is about getting all pictures in different webpages from a website via internet spider --Python.

I've known %d is a integer decimal in Line 1;
And someone has told me the usage of format is the version 2 of Python, but he couldn't tell me more about it.

Would someone please tell me the uage of 'format' in Line 3 of the code above?
1. Specifically, what are the parameters in the bracket of the format?
2. Does the first parameter- in this case 'url', stands for the string that I am going to repace?
3. There needn't to use a comma to separate url from %pageNum?
4. I've searched this usage from the Internet, but got nothing. Would you tell me what keywords are for searching it--- the usage of format in version 2, or could you provide me with the relevant links about this? I would like to learn the grammar of 'format'.

Thank you!

PS. English is not my native language. If my words can't be understood, please let me know.

 

[Malcolm]

Hi there!

Welcome to Code Forum!

Apologize for the delay in responses! Let's see if we can get someone to help you with this!

@Ghost, @Krusty the Senile, @swift do you guys think you could help with these questions?

 

[Krusty the Senile]

I was testing this in repl.it:

url = 'https://www.qiushibaike.com/pic/page/%d/?s=5184961'
for pageNum in range(1,3):
  new_url = format(url %pageNum)
  print(new_url)

url2 = 'https://www.qiushibaike.com/pic/page/{}/?s=5184961'
for pageNum in range(1,3):
  new_url = url2.format(pageNum)
  print(new_url)

The second version is what I think is python 3 compatible. They both produce the same result. Looks like in python 3 '%' based placeholders are replaced with '{}'. I'm not sure how or why "format" in python 2 is the way it is, but I've never really had a chance to deep dive into python.

References: https://pyformat.info/ https://docs.python.org/3/library/string.html#formatspec