Thang String

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

//remove redundant spaces in a string s

void removeRedSpaces(char s[]) {
    int n, low, up, i, j; char x[100];
    n = strlen(s);
    i = 0; j = n - 1;
    while(i < n && s[i] == ' ') i++;
    low = i;
    while(j > 0 && s[j] == ' ') j--;
    up = j;
    if(low > up) {
        strcpy(s, "");
        return;
    }
    strcpy(x, "");
    i = low; j = 0;
    while(i <= up) {
        while(i < up && s[i] == ' ') i++;
        while(i <= up && s[i] != ' ') x[j++] = s[i++];
        if(i <= up) x[j++] = ' ';
    }
    x[j] = '\0';
    strcpy(s,x);
}
void split( char s[], char out[][30], int &length) //tach cac tu trong 1 chuoi
{
    removeRedSpaces(s);
    int i = 0, j, k = 0;
    while ( i < strlen(s))
    {
        for ( j = i; s[j] != '\0' && s[j] != ' '; j ++)

            out[ k ][ j - i ] = s[j];
            out[ k ][ j - i ] = '\0';
            i = j + 1;
            k++;
    }
    length = k;
}

//Enter data for a string s
void input(char s[]) {
    printf("Enter a string s = ");
    fflush(stdin);
    gets(s);
}

//Display a string s
void display(char s[]) {
    printf("%s\n",s);
}

void fun(char s[]) {
    int i, j, n;
    char x[100][30], temp[30];
    split(s, x, n);
    for (i = n - 5; i < n ; i++)
        for (j = i + 1; j < n; j++)
            if (strcmp(x[i],x[j]) > 0)
                { //doi cho
                    strcpy(temp,x[i]);
                    strcpy(x[i],x[j]);
                    strcpy(x[j],temp);
                }

    // rebuild
    int length = strlen(s);
    strcpy(s, "");
    for (i = 0; i < n; ++i) {
        strcat(s, x[i]);
        strcat(s, " ");
    }
    s[length] = '\0';
}

int main()
{
    system("cls");
    printf("\nTEST Q5 (2 marks):\n");
    char s[100];
    input(s);
    printf("\nThe original string:\n");
    display(s);
    printf("\nThe string after processing:\n");
    fun(s);
    display(s);
    //==THE OUTPUT AFTER THIS LINE WILL BE USED TO MARK YOUR PROGRAM==
    printf("\nOUTPUT:\n");
    display(s);
    printf("\n");
    system ("pause");
    return(0);
}