This should work pretty good,...

Changing a string from a specific line in text file

Can anyone tell me how to change the value of loan of a member here in my program? Like let's say I want to change Anne's loan value from 750 to 1000, how can I change only hers and keep the rest? i tried doing the readlines() method but I still cant get to change it, tried researching about it on stackoverflow too but still cant get something out of it. Any help would be appreciated!

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with open('abc.txt','w') as f:
    f.write("Members\t\tLoans"+"\nMark\t\t500"+"\nSteve\t\t1000"+'\nAnne\t750'+'\nAlpha\t520')

a=input("Enter name: ")
b=input("Enter new loan: ")
index = 0
with open('abc.txt','rt') as f:
    lines = f.readlines() #readlines is crucial here
    for i in range(len(lines)):#Find index of line where user is 
      if a in lines[i]:
        index = i 
    #now have index replace value
    mainStr = lines[index]
    originalStr = mainStr #preserve original value
    curNum = int(''.join(filter(str.isdigit, mainStr))) #find current loan
    mainStr = mainStr.replace(str(curNum), str(b)) #change value of loan
    for i in range(len(lines)): #replace value of original loan
      if originalStr in lines[i]:
        lines[i] = mainStr
    lines = "".join(lines) #make it into a big string like before
    print(lines)

with open('abc.txt','w') as f:
    f.write(lines)

This should work pretty good, supports the same file export that you had in your original code and can support more people being added.

please upvote if this helped

@c4syner Its giving me an error with line 15 cause of integer conversion error.

@ZestyLad just make sure you're putting the literal name of the individual. Instead of putting mark put Mark for example.

@c4syner Oh yeah, how dumb of me, its working now, thanks!