用C语言怎么实现浮点数的四舍五入，保留两位小数点 C语言编写程序，对一个double型数据进行四舍五入，要求保...
C\u8bed\u8a00\u5982\u4f55\u5b9e\u73b0\u8f93\u51fa\u6d6e\u70b9\u6570\u5c0f\u6570\u70b9\u4e24\u4f4d\uff08\u56db\u820d\u4e94\u5165\u6cd5\uff09\uff0c\u4f46\u82e5\u5c0f\u6570\u70b9\u6700\u540e\u4f4d\u4e3a\u96f6\u5219\u820d\u53bb\uff1f\uff1f\u53ef\u4ee5\u901a\u8fc7sprintf\u51fd\u6570\u5b9e\u73b0\u6570\u5b57\u56db\u820d\u4e94\u5165\u8f6c\u5b57\u7b26\u4e32\uff0c\u901a\u8fc7\u5904\u7406\u5b57\u7b26\u4e32\uff0c\u5b9e\u73b0\u6240\u9700\u529f\u80fd\uff0c\u5177\u4f53\u4ee3\u7801\uff0c
#include
int main(int argc, char *argv[])
{
char buffer[40];//\u5b58\u50a8float\u6570\u636e
float fnum=12.396;//\u5f85\u6d4b\u8bd5\u6570\u636e
sprintf(buffer,"%.2f",fnum);//\u56db\u820d\u4e94\u5165\u8f6c\u5316\u4e3a\u5b57\u7b26\u4e32
int i=0;
for(;*(buffer+i)!='.';i++);//\u7edf\u8ba1\u5c0f\u6570\u70b9\u7684\u4f4d\u7f6e
if(*(buffer+i+2)=='0')//\u5904\u7406\u5c0f\u6570\u70b9\u540e\u7b2c\u4e8c\u4f4d\u5b57\u7b26\uff0c\u5982\u679c\u4e3a0\uff0c\u66ff\u6362\u4e3a'\0'
*(buffer+i+2)='\0';
printf("\u56db\u820d\u4e94\u5165\u540e\uff0c\u6570\u636e\u53d8\u4e3a\uff1a%s\n,",buffer);
return 0;
}
float \u4e3a\u5355\u7cbe\u5ea6\u6d6e\u70b9\u578b\u6570\u636e\uff0c\u5728Turbo C\u4e2d\u5355\u7cbe\u5ea6\u578b\u53604\u4e2a\u5b57\u8282\uff0832\u4f4d\uff09\u5185\u5b58\u7a7a\u95f4\uff0c\u5176\u6570\u503c\u8303\u56f4\u4e3a3.4E-38\uff5e3.4E+38\uff0c\u53ea\u80fd\u63d0\u4f9b7\u4f4d\u6709\u6548\u6570\u5b57\u3002\u5efa\u8bae\u8f93\u5165\u91c7\u7528\u5b57\u7b26\u4e32\u5f62\u5f0f\uff0c\u8fd9\u6837\u7edf\u8ba1\u4e0d\u4f1a\u51fa\u504f\u5dee\uff0c\u4f7f\u7528\u6570\u5b57\u65f6\uff0c\u4f7f\u7528double atof( const char *str )\u51fd\u6570\u8f6c\u6362\uff1b\u5982\u679c\u4f7f\u7528\u6570\u5b57\uff0c\u7cfb\u7edf\u4f1a\u81ea\u52a8\u88650\u7684\uff0c\u4e0e\u5b9e\u9645\u671f\u671b\u4e0d\u7b26\u3002
\u4f8b\u5982double\u578b\u7684\u6570\u636e\u4e3aa=5.1413\uff0c\u7a0b\u5e8f\u5982\u4e0b\uff1a
#incloud
main( )
{
double a\uff1b
printf("\u8bf7\u8f93\u5165\u4e00\u4e2adouble\u578b\u6570\u636e\uff1a\u201d\uff09\uff1b
a= int (a*100+0.5)/100 \uff1b
printf("%lf",a)\u3002
}
\u8fd9\u65f6\u5019printf\u8f93\u51fa\u7684\u7ed3\u679c\u5c06\u662f5.14\u3002
\u6269\u5c55\u8d44\u6599\uff1a
C\u8bed\u8a00\u7f16\u5199\u7a0b\u5e8f\uff0c\u5bf9double\u578b\u6570\u636e\u8fdb\u884c\u56db\u820d\u4e94\u5165\uff0c\u4fdd\u7559\u4e09\u4f4d\u6709\u6548\u6570\u5b57\uff0c\u7a0b\u5e8f\u5982\u4e0b\uff1a
\u8fd9\u91cc\u4ee5b=8.8888
#incloud
main( )
{
double b\uff1b
printf("\u8bf7\u8f93\u5165\u4e00\u4e2adouble\u578b\u6570\u636e\uff1a\u201d\uff09\uff1b
b= int (b*1000+0.5)/1000\uff1b
printf("%lf",b)\u3002
}
\u8fd9\u65f6\u5019printf\u8f93\u51fa\u7684\u7ed3\u679c\u5c06\u662f8.889\u3002
C语言怎么实现浮点数的四舍五入，保留两位小数的设计过程为：
定义浮点点数变量df，输入浮点数
浮点数df扩大100倍
浮点数df增加0.5
利用floor()函数得到最接近df数，但不大于df的整数（完成四舍五入）。不能用int强制转换，否则，数据超过int范围就会出现错误。
浮点数df缩小100倍得到有两位小数的浮点数
按%.2f输出结果。
参考代码：
#include <stdio.h>
#include <math.h>
void main()
{
double df=0;
printf("input d: "); scanf("%lf", &df );
df *= 100 ;
df += 0.5 ;
df =floor(df);
df /= 100;
printf("d=%.2f
", df );
}
加0.5强制转int。这是取到整数的方法。其他位数道理差不多。2位的话你先乘100，加0.5强制转int，然后除回100。注意类型转换。除100要转double。
float a=10.123;
a=((int)((a*100+5)/100))/100.0;//这个值应该就是保留两位小数点的值吧
printf("%4.2f",a);类似的，前面一个4是字的位数，后面一个2是两位小数
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