web应用程序未执行减法运算Python

Question

我正在尝试创建一个web应用程序，它的一个功能是将数字加、减、乘，这些数字以空格分隔的列表形式实现，它们都可以工作，但是减法给了我奇怪的结果，例如，如果我尝试键入6 2，预期结果可能是4，但现在它给了我-2，我相信这是因为它从索引0中减去，所以它只给出第二个数字，所以我将它改为int（form_text[0]），但现在它给了我索引器：字符串索引超出范围，我确定我键入了两个数字

@app.route('/add_numbers', methods=['GET', 'POST'])
def add_numbers_post():
# --> ['5', '6', '8']
# print(type(request.form['text']))
if request.method == 'GET':
    return render_template('add_numbers.html')

elif request.method == 'POST':
    form_text = request.form['text'].split()
    print(request.form['text'].split())
suma_total = 0
resta_total = int(form_text[0])
multiplicacion_total = 1
try:
    for str_num in form_text:
        suma_total += int(str_num)
        resta_total -= int(str_num[1])
        multiplicacion_total *= int(str_num)
    return render_template('add_numbers.html', result_suma=str(suma_total), result_multiplicacion=str(multiplicacion_total), result_resta=str(resta_total))
except ValueError:
    return "Easy now! Let's keep it simple! 2 numbers with a space between them please"

Answer 1

发生这种情况的原因是，您正在从resta_total（0）中的“for str_num in request.form[“text”].split（）”减去所有数字。resta_total变量应设置为request.form[“text”].split（）中的第一个整数。试试这个

@app.route('/add_numbers', methods=['GET', 'POST'])
def add_numbers_post():
#  > ['5', '6', '8']
# print(type(request.form['text']))
form_text = []
if request.method == 'GET':
    return render_template('add_numbers.html')

elif request.method == 'POST':
    form_text = request.form['text'].split()
    print(request.form['text'].split())
suma_total = 0
resta_total = int(form_text[0]) - int(form_text[1])
multiplicacion_total = 1
try:
    for str_num in request.form['text'].split():
        suma_total += int(str_num)
        multiplicacion_total *= int(str_num)
    return render_template('add_numbers.html', result_suma=str(suma_total), 
result_multiplicacion=str(multiplicacion_total),result_resta=str(resta_total))
except ValueError:
    return "Easy now! Let's keep it simple! 2 numbers with a space between them please"

请注意，这假设表单_文本[0]有一个值。您还可以将for循环更改为“for str_num in form_text”

要处理两个以上整数的减法运算

idx = 0
for str_num in form_text:
    suma_total += int(str_num)
    multiplication_total *= int(str_num)
    if idx > 0:
        resta_total -= int(str_num)
    else:
        resta_total = int(str_num)
    idx += 1