strtok in C/C++ Program - Code implementation - string tokenizer

#include<iostream>
#include <inttypes.h>
#include <string.h>
#include <stdio.h>

using namespace std;

char* my_strtok(char *inp, char *delim);

main()
{
        char src[128] = {'\0'};
        char delim[16] = {'\0'};

        char *out;

        cout << "enter input string src: ";
        gets(src);
        cout << "enter input string dilimiter: ";
        gets(delim);

        cout << "src is " << src << endl;
        cout << "delimiter is " << delim << endl;

        out  = my_strtok(src, delim);  

        while(out != NULL) {
                cout << "token is " << out << endl;
                out = my_strtok(NULL, delim);
        }  
}

char *my_strtok(char *inp, char *deli) {

        static char *start = NULL;
        char *ch = NULL, *delim = NULL, *ret = NULL;
        uint32_t num_chars = 0;

        if (inp != NULL) {
                start = inp;
        }  

        if (start == NULL || deli == NULL) {
                return NULL;
        }  

        ch = ret = start;

        while (*ch != '\0') {
                delim = deli;
                while(*delim != '\0') {
                        if (*ch == *delim) {
                                *ch = '\0';
                                if (num_chars > 0) {
                                        start = ch+1;
                                        return ret;
                                } else {
                                        ret = ch+1;
                                        break;
                                }
                        }
                        delim++;
                }
                ch++;
                num_chars++;
        }
        if (*ch == '\0') {
                start = NULL;
                if (inp == NULL && strlen(ret) != 0) {
                        return ret;
                }
        }
        return NULL;
}

Given an integer find the immediate larger integer which is a palindrome

// #palindrome #C #Programming #String 

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

typedef unsigned int uint;

uint find_next_palin(uint inp);

main()
{
        uint num;
        printf("enter the number: ");
        scanf("%u", &num);

        uint ret = find_next_palin(num);

        printf("next palindrome is %u\n", ret);
}

uint find_next_palin(uint inp)
{
        char buff[32];
        uint ret, i1 =0, i2 =0, i = 0;

        sprintf(buff, "%d", inp);

        int len = strlen(buff);

        if (len == 1) {
                return inp;
        }

        if (len % 2 == 0) {
                i1 = buff[len/2 -1] - '0';
                i2 = buff[len/2] - '0';

                if (i1 < i2) {
                        buff[len/2 -1] = i1 + '0'+1;
                }
                for (i = 0; i < len/2; i++) {
                        buff[len/2+i] = buff[len/2-i-1];
                }
        } else {
                i1 = buff[len/2 -1] - '0';
                i2 = buff[len/2 +1] - '0';

                if (i1 < i2) {
                        buff[len/2 -1] = i1 + '0'+1;
                }
                for (i = 0; i < len/2; i++) {
                        buff[len/2+i+1] = buff[len/2-i-1];
                }
        }

        sscanf(buff, "%u", &ret);
        return ret;
}                                                                                                                                                                                  

Length of the longest substring without repeating characters

length of the longest substring without repeating characters in a given string

Reverse a string

C/C++ solution:

using namespace std;

#include<iostream>
#include<string.h>

string reverse(string input);

int main() {
        string input;
        cout << "Enter the string : " ;
        getline(cin, input);
        string output = reverse(input);
        cout << "Revered string :" << output << "\n";
}

string reverse(string input) {
        int len = input.length();
        int i = 0;
        char tmp;
        while(i < len/2) {
                tmp = input[i];
                input[i] = input[len -i -1];
                input[len - i - 1] = tmp;
                i++;
        }  
        return input;
}

Replace blanks with a string in a given string

Problem - Given a string, replace all blanks with "%20"

C/C++ solution


#include <iostream>
#include <string.h>

using namespace std;

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

        string input = "i am boy. You are Mrs Smith. ";

        int i  = 0;

        int len = input.size();

        cout << "input len before replace = " << len << endl;

        while (i < len) {
                if ( input[i] == ' ') {
                        input.replace(i, 1, "%20");
                        len = len + 2;
   
                }  

                i++;
        }  

        cout << "input = " << input << endl;

        cout << "input len after replace = " << input.size() << endl;
}

 ./a.out 

input len before replace = 29

input = i%20am%20boy.%20You%20are%20Mrs%20Smith.%20

input len after replace = 43

String rotation

/* Program to check given two strings s1 and s2, if one is rotation of
 * other one. For example student is rotation of dentstu.
 */
#include <iostream>
#include <string.h>

using namespace std;

main() {
        string s1, s2;
   
        cout << "Enter both the strings ";

        cin >> s1;
        cin >> s2;

        string temp = s1+s1;

        if (temp.find(s2) == string::npos) {
                cout << s1 << " and " << s2 << " are not rotation of each other." << endl;
        } else {
                cout << s1 << " and " << s2 << " are rotation of each other." << endl;
        }  

}

$ ./a.out 

Enter both the strings student dentstu

student and dentstu are rotation of each other.

$ ./a.out 

Enter both the strings abc acb

abc and acb are not rotation of each other.

Check if unique characters in a string

C/C++ solution:

#include <string.h>
#include <iostream>

using namespace std;

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

        string input ;
        cout << "Input string: ";
        cin >> input;

        bool val[26]; // assuming only english alphabets
        fill_n(val, 26, false);//{ [0 ... 25] = false };

        int len = input.size();

        if (len > 26) {
                cout << "string does not have unique characters." << "\n";
                return 0;
        }  
        while (len >= 0) {
                if(val[tolower(input[len-1]) - 'a'] == true) {
                        cout << "string does not have unique characters." << "\n";
                        break;
                } else {
                        val[tolower(input[len-1]) - 'a'] = true;
                }  
                len--;
           
        }  
        if (len < 0) {
                        cout << "string has all unique characters." << "\n";
        }  
}

Compress String

/* compress the string for example aabbbcccccdeff should become a2b3c5d1e1f2
 * if compress string length remain same as original string then return
 * original string */

using namespace std;

#include <iostream>
#include <string.h>
#include <stdio.h>

main() {

        string input;
        cout << " enter input string to be compressed: ";
        cin >> input;

        string::size_type len = input.size();

        string::size_type orig_len = len;

        string::size_type i = 0;

        int sameCharCount = 1;

        bool in_progress = false;

        char buf[10];

        while (i < len) {
   
                if (input[i] == input[i+1]) {
                        in_progress = true;
                        sameCharCount++;
                } else if (in_progress) {
                        in_progress = false;
                        sprintf(buf, "%d", sameCharCount);
                        input.replace(i-sameCharCount+2, sameCharCount-1, buf);

                        len = len - sameCharCount + 1 + strlen(buf);

                        i = i - sameCharCount + 1 + strlen(buf);

                        sameCharCount = 1;

                } else {

                        input.insert(i+1, "1");

                        i++;

                        len++;

                }

                i = i + 1;

        }

        if (input.size() < orig_len) {

                cout << "changed string: " << input << endl;

        } else {

                cout << "string was not compressed" << endl;

        }

}

$ ./a.out 

 enter input string to be compressed: aaabb

changed string: a3b2

$ ./a.out 

 enter input string to be compressed: ab

string was not compressed

$ ./a.out 

 enter input string to be compressed: acc

string was not compressed

$ ./a.out 

 enter input string to be compressed: b

string was not compressed

$ ./a.out 

 enter input string to be compressed: bc

string was not compressed

$ ./a.out 

 enter input string to be compressed: abc

string was not compressed

$ ./a.out 

 enter input string to be compressed: aaabbbbbbbbbbbbddddddddddd

changed string: a3b12d11