Question

我正在尝试检查用户是否提供了数字而非字母的输入。当给出非数字值时，我想打印一条警告错误消息，如“格式不正确”。

这是我的源代码：

-(IBAction)btnPressed{

    NSString *firstString = textFiled1.text;
    NSString *secondString = textFiled2.text;
    NSString *thirdString = textFiled3.text;

    int num1;
    int num2;
    int num3;

    int output;

    num1 = [firstString intValue];
    num2 = [secondString intValue];
    num3 = [thirdString intValue];

    output = (num1 + num2) / num3;

    lable1.text = [NSString stringWithFormat:@"%d",output];
}

Answer 1

使用NSNumberFormatter。如果输入参数不是有效数字，则导出的数字将为nil。

NSNumberFormatter * f = [[NSNumberFormatter alloc] init];
[f setNumberStyle:NSNumberFormatterDecimalStyle];
num1 = [f numberFromString:firstString];
[f release];

if (num1 == nil) {
// throw exception
}

Answer 2

我就是这样做的：

NSCharacterSet *nonNumbers = [[NSCharacterSet decimalDigitCharacterSet] invertedSet];
if ([firstString rangeOfCharacterFromSet:nonNumbers].location != NSNotFound) {
    // firstString has non-number characters in it!
}

检查输入值

2 个答案: