C/C++ How to convert back int to string (a word)? -

in c i'm reading string txt file, example string "hello", have my:

f=fopen("text.txt","r"); fscanf(f,"%s\n",string); 

now, if want convert string hex , decimal, can this:

for (i=0; i<strlen(string); i++) {    sprintf(st, "%02x", string[i]);  //convert hex    strcat(hexstring, st);     sprintf(st, "%03d", string[i]);  //convert dec    strcat(decstring, st); } 

now, question is: want inverse operation, how? output if convert "hello"

   hex-> 68656c6c6f    dec-> 104101108108111 

from "68656c6c6f" or "104101108108111" want go "hello", how can this?

(basically want website: http://string-functions.com/; string hex converter, hex string converter, decimal hex, converter, hex decimal converter)

the challenge realize have string of hex , string of decimal, meaning have character string representation of values, not values themselves. need convert string representations appropriate numeric values before converting original string.

presuming have hex string representation of two-byte hex character pairs, following return original string hello 68656c6c6f:

/* convert hex string original */ char hex2str[80] = {0}; char *p = hex2str; int = 0; int itmp = 0;  while (hex[i]) {     sscanf (&hex[i], "%02x", &itmp);     sprintf (p, "%c", itmp);     p++;     i+=2; } *p = 0;  printf ("\n hex2str: '%s'\n\n", hex2str); 

output

$ ./bin/c2h2c < <(printf "hello\n")   hex2str: 'hello' 

---

short working example

#include <stdio.h> #include <string.h>  #define maxs 64  int main (void) {      char hex[] = "68656c6c6f";     char hex2str[maxs] = {0};     char *p = hex2str;     int itmp = 0;     int = 0;      /* convert hex string original */     while (hex[i])     {         sscanf (&hex[i], "%02x", &itmp);         sprintf (p, "%c", itmp);         p++;         i+=2;     }     *p = 0;      printf ("\n hex2str: '%s'\n\n", hex2str);      return 0; } 

output

$ ./bin/c2h2c   hex2str: 'hello'