python自定义isnumber函数判断字符串是否为数字，pythonisnumber,''' isnumeri

python自定义isnumber函数判断字符串是否为数字，pythonisnumber,''' isnumeri

''' isnumeric.pytest a numeric string s if it's usable for int(s) or float(s)'''def isnumeric(s):    '''returns True if string s is numeric'''    return all(c in "0123456789.+-" for c in s)# test module ...if __name__ == '__main__':    print(isnumeric('123'))      # True    print(isnumeric('-123.45'))  # True    print(isnumeric('+3.14'))    # True    print(isnumeric('$99.95'))   # False