程序帮助！ 用户点击进入程序后，程序结束

Question

Ok I am making a program that reads two characters from the user and then prints the ASCII letters between those two characters. The problem is that when the program runs it prompts the user to enter the first character and once the user hits enter the program ends. What am I missing?

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[]){


      char firstchar;
      char secondchar;
      int variable;
      int highest;
      int lowest;
      char ASCIvariable;

      printf("Please enter a character. ");
      scanf("%d", &firstchar);

      printf("Please enter another character. ");
      scanf("%d", &secondchar);

      if(firstchar < secondchar) 
      {
         secondchar = highest;
         firstchar = lowest;
      }else{
         firstchar = highest;
         secondchar = lowest;
      }

      variable = lowest;

      for ( variable != highest; variable < highest; variable++ )
      {
          variable = ASCIvariable;
          printf(ASCIvariable);
      }

      return 0;
}

I clearly also don't understand how to post code on this site. I need four spaces manually entered before EVERY line of code?

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Update here is the current code also control k will not allow paste....

#include <stdio.h>
#include <stdlib.h>



 int main(int argc, char *argv[]) {


    char firstchar;
  char secondchar;
   int variable;
  int highest;
  int lowest;
  char ASCIvariable;

  printf("Please enter a character. ");
  scanf(" %c", &firstchar);

  printf("Please enter another character. ");
  scanf(" %c", &secondchar);

  if(firstchar < secondchar) 
  {
 highest = secondchar;
 lowest = firstchar;
}
  else
  {
  highest = firstchar;
  lowest = secondchar;
}

  variable = lowest;


 for (variable != highest; variable <= highest; variable++ )
  {
        ASCIvariable = variable;
      printf("%c ", ASCIvariable);

  }


    return 0;
}

It successfully allows the user to enter both characters and then prints the letters between the two. I think that is correct?

Answer 1

Change your code to:

printf("Please enter another character. ");
scanf(" %c", &secondchar);  /* Note the extra space and %d is changed to %c*/

Also change your for loop to:

for ( ; variable <= highest; variable++ ) /* Should be <= */ {
   ASCIvariable = variable; /* Reverse */
   printf("%c", ASCIvariable); /* %c */
}

Your assignations are also incorrect:

if(firstchar < secondchar) 
{
 highest = secondchar;
 lowest = firstchar;
}
else
{
  highest = firstchar;
  lowest = secondchar;
}

a = b; means copy contents of b into a .

Answer 2

Using wrong format specifier might lead to UB. You need to scan a character

scanf("%c", &firstchar);

Then flush the newline char using

scanf(" %c",&secondchar);

The space before the %c consumes the newline char.

Answer 3

1)You must get input with format specifier %c for characters

2)You must consume the newline after entering first character

3) You seem to be confused with assignment statements

a=b assigns the valure of b to a and not the other way around.

printf("Please enter a character. ");
scanf(" %c", &firstchar);
//The space before %c will consume the newline

printf("Please enter another character. ");
scanf(" %c", &secondchar);

if(firstchar < secondchar) 
{
    highest=secondchar ;
    lowest=firstchar ;
}
else
{
    highest=firstchar;
    lowest= secondchar ;
}

//Changed the for loop to get characters between two inputs
variable = lowest+1;
for ( ; variable < highest; variable++ )
{
     ASCIvariable= variable ;
     printf("%c ", ASCIvariable);

}