log和logf

用C/C++处理数据的时候,如果数值比较大就得注意数据类型。比如这个log函数的问题。 log接受double类型的参数,而logf接受float类型。 比如这段代码: #include #include int main() { double x = 4.4e52; printf(“log(%lf) = %f\n”, x, log(x)); printf(“log(%lf) = %f\n”, x, logf(x)); return 0; } linux/gcc下的输出是 log(43999999999999999701721741671911630964315171445538816.000000) = 121.216029 log(43999999999999999701721741671911630964315171445538816.000000) = inf