如何將此變量與.txt文件中的特定變量添加到同一行？

Question

我希望能夠將quantity添加到與.txt文件中的匹配crop相同的行上。 但是，此刻我收到錯誤： ValueError: '(whichever string is contained within crop)' is not in list' 。 我相信這是因為我需要拆分每行的元素，以便僅將crop與每行的第一個元素進行比較。

crop = input("Which crop? ")
quantity = input("How many? ")

with open ('cropdatabase.txt', 'a+') as file:
 lines = file.readlines
 index = lines.index(crop)
 lines[index] += ' ' + str(quantity)

file.close ()

.txt文件的格式如下

Answer 1

它不是簡短/有效的解決方案，但它的工作原理是：

crop = input("Which crop? ")
quantity = input("How many? ")
def crop(crop, quantity):
        file =  open('cropdatabase.txt',"r+")
        lines = file.readlines()       
        linenumber = 0
        for i in range(len(lines)):
            if crop == lines[i].split()[0]:
                linenumber = i
                break
        lines[linenumber] = lines[linenumber][:-1]
        lines[linenumber]+= " " + str(quantity)+'\n'
        text = "".join(lines)
        file.close()
        file2  = open('cropdatabase.txt',"w")
        file2.write(text)
        file2.close()

crop(crop, quantity)