读取浮点数并以十进制表示法，指数表示法和p表示法打印

#include <stdio.h>
int main(void) 
{
  float flt_input;

  printf("Enter a floating-point value: ");
  scanf("%f", &flt_input);
  printf("Fixed-point notation: %f/n", flt_input);
  printf("Exponential notation: %e/n", flt_input);
  printf("P notation: %a/n", flt_input);

  return 0;
}