为什么我的代码在 output 中显示奇怪的数字？

Question

This is a program to print a histogram of the frequencies of different characters in its input. It counts uppercase and lowercase letters together.

The characters should be printed in increasing order of their ASCII value.

#include<string.h>
#include<stdio.h>
#include<ctype.h>
int main()
{
    char str[100], new[100];  
    int  i,j,count=0,n;
    char temp; 

    fgets(str, 100, stdin);

    //convert upper chars to lower chars
    for(i=0;i<strlen(str);i++){
        new[i] = tolower(str[i]);

    }    

    //assign n to the length of the string
    for(j=0;new[j];j++);
    n=j; 

    //sort the string in ascending order
    for (i = 0; i < n-1; i++) {
        for (j = i+1; j < n; j++) {
            if (new[i] > new[j]) {
                temp = new[i];
                new[i] = new[j];
                new[j] = temp;
            }
        }
    }

    //check and print the count
    for(i=0;i<n;i++)  
    {
        count=1;
        if(new[i])  
        {
          for(j=i+1;j<n;j++)  
          {   
            if(new[i]==new[j])
            {
                 count++;
                 new[j]='\0';   //make the sec char 0
            }
          }  
          printf("%c %d \n",new[i],count);
       }
    } 


    return 0;
}

Answer 1

for(j=0;new[j];j++); fails as new is not a string .

null character never assigned in new[] before for(j=0;new[j];j++);

Answer 2

It's not clear what bizarre numbers you mean from the output. All the counts of characters look correct.

If you mean the weird 1 at the start of the output, then I expect the "gotcha" is that your input (and output) includes the newline character.

> man fgets

fgets() reads in at most one less than size characters from stream and stores them into the buffer pointed to by s. Reading stops after an EOF or a newline. If a newline is read, it is stored into the buffer.

So when you sort the characters, the newline character will be first.

You could solve this a few different ways, but a simple one is to only output printable characters, eg

    if(isprint(new[i]))  
        printf("%c %d \n",new[i],count);