Program to print all substrings of a given string - c

Question

I am having trouble creating an algorithm that prints all substrings of a given string. This is my implementation now:
#include <stdio.h>
#include <string.h>
// Function to print all sub strings
void subString(char str[], int n)
{
// Pick starting point
for (int len = 1; len <= n; len++)
{
// Pick ending point
for (int i = 0; i <= n - len; i++)
{
// Print characters from current
// starting point to current ending
// point.
int j = i + len - 1;
for (int k = i; k <= j; k++) {
char data[n];
sprintf(data, "%d", str[k]);
printf("%s\n", data);
}
}
}
}
// Driver program to test above function
int main()
{
char str[] = "abc";
subString(str, strlen(str));
return 0;
}
My code is not converting integers to strings. Could someone help me figure out what's wrong?

Answer 1

The logic seems basically fine, but the formatting doesn't make much sense as this prints the digit values for each character and adds a newline for each print call. If you print the characters directly using %c formatting and only print a newline once you've emitted a full substring you'll have a more sensible result.
#include <stdio.h>
#include <string.h>
void subString(char *str, int n)
{
for (int len = 1; len <= n; len++)
{
for (int i = 0; i <= n - len; i++)
{
for (int j = i; j <= i + len - 1; j++)
{
putchar(str[j]);
}
puts("");
}
}
}
int main()
{
char str[] = "abc";
subString(str, strlen(str));
return 0;
}
Output:
a
b
c
ab
bc
abc
A little nitpick: I'd suggest calling this function printSubStrings since it produces a side effect. The name subString doesn't seem to match the contract particularly well.
You can also use the "%.*s" format to extract the substring chunk you want instead of the innermost loop:
void print_substrings(char *str, int n)
{
for (int len = 1; len <= n; len++)
{
for (int i = 0; i <= n - len; i++)
{
printf("%.*s\n", len, str + i);
}
}
}

Answer 2

#include<bits/stdc++.h>
using namespace std;
int main()
{
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
string str;
cin >> str;
for (int i = 0; i < str.size(); i++) {
for (int len = 1 ; len <= str.size() - i; len++)
{
cout << str.substr(i, len) << endl; // prints substring from starting index i till length len
}
}
return 0;
}
Input:
abcd
Output:
a
ab
abc
abcd
b
bc
bcd
c
cd
d