在Python中将字符串数据转换为整数

Question

我有一个以下程序，该程序从csv文件中读取一些数据，但它似乎拒绝所有尝试将“标记”数据读取为整数或以后再将其转换为整数的尝试。我将这个程序基于另一个我具有的功能，它具有完整的功能，唯一的真正区别是整数字段是我正在运行的程序中的浮点数。

我尝试在“ for counter ...”行之后将以下行输入到findHighest函数中。

**Students[0].marks = int(Students[0].marks)**

该代码运行，但未在数据中找到最高编号（最高编号为100时返回96，第二最高编号为96）。我还尝试过更改以下行...

Students[counter].marks = row[3]

并将其更改为...

**Students[counter].marks = int(row[3])**

这给了我以下错误：

ValueError：以10为底的int（）无效文字：

我在这里想念什么？ ：-/

导入csv

class Student:
    def __init__(self,forename,surname,form,marks):
        self.forename = ""
        self.surname = ""
        self.form = ""
        self.marks = 0

def readFile():
    Students = []
    filename = "pupils.csv"
    csv_file = open(filename, "r")
    reader = csv.reader(csv_file)
    counter = 0
    for row in reader:
        Students.append(Student("", "", "", 0)) 
        Students[counter].forename = row[0] 
        Students[counter].surname = row[1] 
        Students[counter].form = row[2] 
        Students[counter].marks = row[3]
        counter = counter + 1
    return Students


def findHighest(Students):
    position=0
    highest = Students[0].marks
    for counter in range(len(Students)):
        Students[counter].marks = int(Students[counter].marks)
        if Students[counter].marks > highest:
            highest = Students[counter].marks
            position = counter
    return highest

def displayHighest(highest):
    print("the highest pupil score was:", highest)

Students = readFile()
highest = findHighest(Students)
displayHighest(highest)

CSV文件：

Answer 1

我猜你有多个问题

def findHighest(Students):
    position=0

#highest is set to a string. You should set highest to 0
    highest = Students[0].marks
    for counter in range(len(Students)):

#why do you always set Students[0] and not Students[counter]. You always convert Students[0] to int.
        Students[0].marks = int(Students[0].marks)

#As a result you always tests string again strings:
        if Students[counter].marks > highest:
            highest = Students[counter].marks
            position = counter
    return highest

这次尝试

Students[counter].marks = int(row[3])

应该是正确的，但ValueError可能表明您的CSV内容并非完全是正确的整数值。请检查您的CSV或处理如下异常： Converting String to Int using try/except in Python

Answer 2

似乎这是CSV文件而不是代码的问题。我从头开始创建了一个新文件，它的Student [counter] .marks = int（row [3]）行工作正常。