新手请教float 类型的基础问题

[baidu_35364666]

float类型的数据 通过计算输出如下：
但是我想让他输出后面不要有多余的0 怎么处理呢，比如下面的就输出 1 0.5 0.05 100

	float i1=1;

	CString ssss;
	ssss.Format("%f",i1);
	AfxMessageBox(ssss);//1.000000

	ssss.Format("%f",i1/2);
	AfxMessageBox(ssss);//0.500000

	ssss.Format("%f",i1/20);
	AfxMessageBox(ssss);//0.050000

	ssss.Format("%f",i1*100);
	AfxMessageBox(ssss);//100.000000

[zgl7903]

  double i1 = 1.0;
  CString ssss;
  ssss.Format("%.*g", 7, i1);  

[schlafenhamster]

g double Signed value printed in f or e format, whichever is more compact for the given value and precision. The e format is used only when the exponent of the value is less than –4 or greater than or equal to the precision argument. Trailing zeros are truncated, and the decimal point appears only if one or more digits follow it.

[baidu_35364666]

引用 1 楼 zgl7903 的回复:

  double i1 = 1.0;
  CString ssss;
  ssss.Format("%.*g", 7, i1);  

谢谢，可以了，但是还是不明白"%.*g", 7 代表的是什么意思

[zgl7903]

Format Specification Syntax: printf and wprintf Functions "%.*g", 7, 相当于 %.7g, 最多7位数， 但是* 可以以变量参数的方式传递格式长度, 比如 ("%.*g", iLen, fVal) If the width specification is an asterisk (*), an int argument from the argument list supplies the value. The width argument must precede the value being formatted in the argument list. A nonexistent or small field width does not cause the truncation of a field; if the result of a conversion is wider than the field width, the field expands to contain the conversion result. g, G The precision specifies the maximum number of significant digits printed. Default Six significant digits are printed, with any trailing zeros truncated.

[schlafenhamster]

ssss.Format("%.7g", i1/2.1); AfxMessageBox(ssss);//0.4761905 “.后7位”