Here are the solution of [Digit Frequency in C Hacker Rank Solution] https://www.chase2learn.com/digit-frequency-in-c-hacker-rank-solution/

include

include

include

include

int main() {

char num[100]; int q=0,w=0,e=0,r=0; int t=0,y=0,u=0,o=0,p=0,a=0; scanf("%s",num); for(int i=0;i<=strlen(num);i++) { if (num[i]=='0') { q++; }
else if(num[i]=='1') { w++; } else if(num[i]=='2') {

      e++;
 }
 else if(num[i]=='3'){
     r++;
 }
  else if(num[i]=='4'){
     t++;
 }
  else if(num[i]=='5'){
     y++;
 }
  else if(num[i]=='6'){
     u++;
 }
  else if(num[i]=='7'){
     o++;
 }
  else if(num[i]=='8'){
     p++;
 }
  else if(num[i]=='9'){
     a++;
 }
 else {
     continue;
 }

} printf("%d %d %d %d %d %d %d %d %d %d ",q,w,e,r,t,y,u,o,p,a); return 0;

}

char arr[100000]; scanf("%s", arr); int d=strlen(arr); int a[9]={0};

for(char i='0'; i<='9'; i++){
    for (int k=0; k<d;k++){
        if(i==arr[k]){
            a[i-48]++;
        }
    }
}
for(int j=0; j<=9;j++){ 
printf("%d"" ", a[j]);
}
// for(int* k=0; k<9;k++){
//     for(int l=0; l<20;l++){
//         if(k==arr[l]){
//         arr[k]==arr[k+1];}
//     }
// }
return 0;

code is here

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

int main() {

    int i, a[9]={0};
    char *s;
    
    s=(char *)malloc(1000*sizeof(char));
    scanf("%s", s);
    
    for (i=0; s[i]!='\0'; i++) {
    if (s[i]>=48 && s[i]<=57) {
    a[s[i]-48]++;
    }
    }
    for (i=0; i<=9; i++) {
    printf("%d ", a[i]);
    } 
    free(s);
    return 0;
}