逐行读取文件并仅在完成后打印

Question

So I am working on doing a "simple" task since like 2h and still can't find the solution, so where is my question : I want to search in a file, line by line, and if no result is found, at the end print something, else call a function.

def DeletItemCheckUp():
    import re
    find = True
    itemNumber = input("\n what is the item you want to delet : ")
    fileItem = open('Data_Item', 'r', encoding='Utf-8')
    for line in fileItem:
        sr = re.search(r'^\b%s\b'%itemNumber,(line.split(';')[0]))
        if (sr == None):
            pass
    print("This item don't exist.")
    fileItem.close()
    if (find == True):
        return itemNumber
        DeletItem()

so here is the problem I have got with different try : 1. Print "This item don't exist." for every line that didn't had my itemNumber. 2. When there was actually no match found, its would not call DeletItem().

objectif of the code : Ask for a item to delet, check in a file if the unique item number exist, if so, call DeletItem() to delet it, else, tell the user that this unique item number don't exist.

Answer 1

Few overlooks in there to achieve what you ask. We are going to use a flag (true/false) to know when we found something, and based on that we will decide whether to call the function or print/return the number.

def DeletItemCheckUp():
    import re
    find = False      # initialize to False
    itemNumber = input("\n what is the item you want to delet : ")
    fileItem = open('Data_Item', 'r', encoding='Utf-8')
    for line in fileItem:
        sr = re.search(r'^\b%s\b'%itemNumber,(line.split(';')[0]))
        if (sr == None):
            continue  # do nothing and continue
        else:
            # we found the number, set the flag and break
            find = True
            break  # no need to continue searching
    fileItem.close()
    if (find):
        DeletItem()           # call the function
    else:
        print("This item don't exist.")

Answer 2

1) replace the pass with your print('This item doesn't exist'). "Pass" means "do nothing."

2) Your DeleteItem() is after the return. Nothing executes after the return because you have returned to the place the function was called from. You want

else:
    DeleteItem()