pset2 readability. cannot compile although int is declared and code is complete. could someone please look into?

Question

#include<cs50.h>
#include<stdio.h>
#include<string.h>
#include<ctype.h>
#include<math.h>

int main (void)
{
    string text=get_string("text:\n");

    // to count letters

    for(int i=0;text[i]!='\0';i++)
    { i=text[i];
    printf("letters: %i\n", i);
    }

    // to count words

     for(int j=1;text[j]=='\0';j++)
      { j=text[j];
    printf("words:%i\n", j);
    }

    // to count sentences

    for(int k=0;text[k]=='.' || text[k]=='?' || text[k]=='!';k++)
    { k=text[k];
    printf("sentences: %i\n",k);
    }
    {
        float l=( i/j)*100;
    float s=( k/j)*100;
    float index = (0.0588*l - 0.296*s - 15.8);
    int g=round(index);

if (g >= 1 && g <=16)
        {
            printf("Grade %i\n", g);
        }
    else
    {
        if (g < 1)
        {
            printf("Before Grade 1\n");
        }
        if (g > 16)
        {
            printf("Grade 16+\n");
        }
}
}
}

#include<cs50.h>
#include<stdio.h>
#include<string.h>
#include<ctype.h>
#include<math.h>

int main(void)

{
    string text = get_string("text:\n");

    // to count letters
    float letters = 0;
    float words = 1;
    float sent = 0;
    int i= 0 ;


   for(i=0;i<strlen(text);i++)
      {if (isalpha(text[i]))
    { letters++;
    }

    // to count words
   if( isspace(text[i]))
      { words++;

    }

    // to count sentences
      if (text[i] == '.' || text[i] == '!' || text[i] == '?')
    { sent++;

    }
 }
   //  printf("letters: %f; words: %f; sentences: %f\n", letters, words, sent);
    { float l = letters / words * 100;
    float s = sent / words * 100;
    float index = 0.0588 * l - 0.296 * s - 15.8;
    int g= round(index);

   // printf("index rounded:%i\n",g);

if (g >= 1 && g <=16)
        {
            printf("Grade %i\n",g);
        }
    else
    {
        if (g < 1)
        {
            printf("Before Grade 1\n");
        }
        if (g > 16)
        {
            printf("Grade 16+\n");
        }
}
}
}

Answer 1

It's a scope problem: When you declare a variable inside a 'for' loop or a function, it only will be available until the loop/function ends. For example in your for loop: for(int i=0;text[i]!='\0';i++) as 'i' is declared and inicialized at the begining of the for loop, as soon as the loop finishes, it'll be destroyed and you won't be able to access to it anymore.

Answer 2

The variables that you create in the for loops only exist within that for loop. You can use the result of a certain iteration of a for loop by eg: including an if function within the for loop to pick up what you are after .