ws7 đáng ghét

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

void input(char s[]){
    printf("\nInput a string: ");
    fflush(stdin);
    gets(s);
}
//HAM DEM XEM BAO NHIEU TU TRONG CHUOI
int countWord(char s[]){
    int word=0;
    for(int i=0; i<strlen(s); i++)
        if(s[i]!=32&&(s[i+1]==32||s[i+1]==NULL)) word++;
    return word;
}
//HAM CAT CHUOI
void cutWord(char s[]){
    int count=0;
    char p[100]; strcpy(p,s);
    printf("The original string: ");
    puts(s);
    printf("Number of words in the string: %d, they are: \n",countWord(s));
    char *token;
    token=strtok(p," \t");
    while(token!=NULL){
        puts(token);
        token=strtok(NULL," \t");
        count++;
    }
}
//HAM VIET HOA DAU TU
void upperWord(char s[]){
    char p[100]; strcpy(p,s);
    printf("The original string: ");
    puts(s);
    printf("The proper form: ");
    for(int i=0; i<=strlen(p); i++){
        if(p[i]==32&&p[i+1]!=32){
            if(p[i+1]>='a'&&p[i+1]<='z') p[i+1]-=32;
        }
        if(p[0]>='a'&&p[0]<='z') p[0]-=32;
    }
    puts(p);
}
//HAM XOA KHOANG CACH
void deleteSpace(char s[]){
    char p[100]; strcpy(p,s);
    printf("The original string: ");
    puts(s);
    printf("The cleaned form: ");
    for(int i=0; i<strlen(p); i++){
        if(p[i]==32&&p[i+1]==32){
            for(int j=i; j<strlen(p); j++)
                p[j]=p[j+1];
            i--;
            p[strlen(p)]=NULL;
        }
    }
    if(p[0]==32){
        for(int i=0; i<strlen(p); i++)
            p[i]=p[i+1];
        s[strlen(p)]=NULL;
    }
    if(s[strlen(p)]==32)
        s[strlen(p)]=NULL;
    puts(p);
}
//HAM CHECK TEN
void checkName(char s[]){
    bool check=true;
    for(int i=0; i<strlen(s); i++){
        if(isalpha(s[i])==0&&s[i]!=32){
            check=false;
            break;
        }
    }
    if(check==true) printf("%s is a valid name\n",s);
    else printf("%s is not a valid name\n",s);
}
int main(){
    char s[100];char next;

    int selection;
    do{
        system("cls");
        printf("Choose one of the following options:\n");
        printf("1. Input a string\n");
        printf("2. Split a string into words\n");
        printf("3. Convert a string into proper form\n");
        printf("4. Remove redundant spaces\n");
        printf("5. Check valid name\n");
        printf("0. Exit\n");
        printf("Your selection (0->6): ");
        scanf("%d", &selection);
        switch(selection){
            case 1: input(s); break;
            case 2: cutWord(s); break;
            case 3: upperWord(s); break;
            case 4: deleteSpace(s); break;
            case 5: checkName(s);break;
            case 0: return 0;
        }
        printf("Enter y/n: ");fflush(stdin);scanf("%c",&next);
    }while(next=='y');

}