写一个方法，把字符串转为数字，比如 str="1234"，变成 int 1234。并且测试这个程序。

Answer 1

def StrToInt(a):
    res ,mult,flag = 0,1,1
    if not isinstance(a,str):
        raise TypeError("a is not str")
    if a[0] =='-' or a[0] == '+':
        if a[0] == '-':
            flag = -1
        a = a[1:]
    for i in range(len(a)-1,-1,-1):
        if '9' =a[i] = '0':
            res +=(ord(a[i]) -48) * mult
            mult = mult *10
        else :
            return 0
    return res * flag

def test_strToInt2(self):
    with pytest.raises(TypeError):
        StrToInt(34)

 

测试用例：
def test_strToInt3(self):
    assert StrToInt('测试赛') == 0

def test_strToInt4(self):
    assert StrToInt('+2147689') == 2147689

def test_strToInt5(self):
    assert StrToInt('45') == 45

def test_strToInt6(self):
    assert StrToInt('1a33') == 0

def test_strToInt7(self):
    assert StrToInt('-5') == -5