//iOS开发Swift版取绝对值方法(绝对值:不懂意思就去看看小学数学)
        print(abs(-12));12
        print(abs(13));13
        print(fabs(12.12));12
        print(fabs(-12.12));12
        print(fabsf(2525.151));2525
        print(fabsf(-2525.151));2525