c - 如何判断用户输入的小数位有多少位？

Question

我正在尝试编写一个程序，该程序采用一个数字和所需的小数位数，然后通过比较该数字与该数字 +1 的距离来对该数字进行适当舍入。

int main() {
double tester;
int numberOfDecimals;

printf("Enter a number to be rounded: ");
scanf("%lf",&tester);
printf("%d rounded to how many decimal places? ",tester);
scanf("%d", &numberOfDecimals);

在我询问他们希望数字四舍五入到的小数位数后，如何检查他们输入的数字有多少位小数？

Answer 1

int main() {
double tester;
int numberOfDecimals;
char strBuf[255+1];
char *decimalPoint;
int decimalPlacesOfInput = 0;

printf("Enter a number to be rounded: ");
fgets(strBuf, sizeof(strBuf), stdin);

decimalPoint=strchr(strBuf, '.');
if(decimalPoint)
   {
   ++decimalPoint;
   while(isdigit(*decimalPoint))
      {
      ++decimalPlacesOfInput;
      ++decimalPoint;
      } 
   }

printf("Number entered with %d decimal places.\n", decimalPlacesOfInput);

tester=atof(strBuf);
printf("%d rounded to how many decimal places? ",tester);
scanf("%d", &numberOfDecimals);
...