I'm trying to write a program that inputs a string (that is actually a sentence) and an array. The function should check if the values in the array are the lengths of each word in the string.

Example 1: This is an example. (The array should be: [4,2,2,7].

Example 2: Space... The final frontier... (The array should be: [5,3,5,8]).

I'm struggling with a few things:

1. How do I check if the length of a word is equal to the value in the array without putting the lengths in another array?
2. Why does my code register symbols like ('.','!'...) as words?
3. Why is my lengthofstring always 0? Is my if-statement wrong?

Here is what I have written so far.

int checklength(const char *str,int array[],int n)
{
    int i,j=0,start=0,end,lengthofword,lengthofstring,isittrue=0;
    while(*(str lengthofstring)!='\0')
    {
        lengthofstring  ;
    }
    
    for(i=0;i<lengthofstring 1;i  )
    {
        if((*(str i)>=32 && *(str i)<=64) || (*(str i)>=91 && *(str i)<=96) || (*(str i)>=123 && *(str i)<=126))
        {
            end=i;
            lengthofword=end-start; //Why is my lengthofword 0 here?
            
            //Here is what I tried for checking if value is in array:
            j  ;
            while(j<n)
            {
                if(array[j]==lengthofword)
                {
                    isittrue=1;
                }
                break;
            }
        }
       start=i 1;  
    }
    return isittrue;
}

CodePudding user response：

1. You check one word at a time and exit when the first length test fails.
2. *(str i)>=32 && *(str i)<=64) matches those symbols and you don't exclude it elsewhere.
3. You operate on uninitialized data which is undefined behavior.

Here is how I would write this:

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

int is_word_len(const char *str, size_t n) {
    size_t i = 0;
    for(; i < n; i  )
        if(!isalpha(str[i]))
            return 0;
    return !isalpha(str[i]);
}

int is_str_lens(const char *str, size_t n, size_t array[n]) {
    // Consider adding checks along these lines:
    // assert(str);
    // assert(*str);
    // assert(n);
    // assert(array);
    size_t offset = 0;
    size_t i = 0;
    for(; str[offset] && i < n; i  ) {
        while(str[offset] && !isalpha(str[offset])) offset  ;
        if(!is_word_len(&str[offset], array[i]))
            return 0;
        offset  = array[i];
    }
    while(str[offset] && !isalpha(str[offset])) offset  ;
    return i == n && !str[offset];
}

int main() {
    struct {
        char *str;
        size_t n;
        size_t *array;
    } tests[] = {
        { "This is an example.", 4, (size_t []) { 4, 2, 2, 7} },
        { "Space... The final frontier...", 4, (size_t []) { 5, 3, 5, 8 } },
        { "...Space... The final frontier...", 4, (size_t []) { 5, 3, 5, 8 } },
        { "Space...", 2, (size_t []) { 5, 2 } },
        { "Babies x", 1, (size_t []) { 6 } }
        { "This", 2, (size_t []) { 2, 2 } }
    };
    for(size_t i = 0; i < sizeof tests / sizeof *tests; i  ) {
        printf("%s: %d\n", tests[i].str, is_str_lens(tests[i].str, tests[i].n, tests[i].array));
    }
}

and output:

This is an example.: 1
Space... The final frontier...: 1
...Space... The final frontier...: 1
Space...: 0
Babies x: 0
This: 0

If you don't want to use isalpha() then re-implement along these lines:

int my_isalpha(int c) {
   return
      c >= 'A' && c <= 'Z' ||
      c >= 'a' && c <= 'z';
}

CodePudding user response：

Your code is hard to read and too complicated. You have very handy standard functions which can help you with your task.

int checklength(const char *str, const size_t *array, const size_t n, const char *delim)
{
    int isittrue = 1;
    size_t cpos = 0;
    char *token;
    char *modifStr = malloc(strlen(str)   1);

    if(modifStr)
    {
        strcpy(modifStr, str);
        token = strtok(modifStr, delim);
        while(token)
        {
            if(array[cpos] != strlen(token))
            {
                isittrue = 0;
                break;
            }
            cpos  ;
            token = strtok(NULL, delim);
        }
    }
    else return -1;
    free(modifStr);
    return isittrue && cpos == n;
}

int main(void)
{
    printf("%d\n", checklength("This is an example.", (size_t[]){4,2,2,7}, 4, " ."));
    printf("%d\n", checklength("Space... The final frontier...", (size_t[]){5,3,5,8}, 4, " ."));
}

https://godbolt.org/z/xnf6sK1cx

You can improve this function by adding parameter checks, checking if number of words is not larger than the number of elements of the array etc. But I have left it for you....