C novice programmer - please explain this error

Question

I'm just starting with C and looking for some examples from Richie’s book. I wrote a small program for understanding arrays of characters, but came across some errors and hoped for some understanding of what I misunderstood:

#include <stdio.h> #define ARRAYSIZE 50 #include <string.h> main () { int c,i; char letter[ARRAYSIZE]; i=0; while ((c=getchar()) != EOF ) { letter[i]=c; i++; } letter[i]='\0'; printf("You entered %d characters\n",i); printf("The word is "); printf("%s\n",letter); printf("The length of string is %d",strlen(letter)); printf("Splitting the string into chars..\n"); int j=0; for (j=0;j++;(j<=strlen(letter))) printf("The letter is %d\n",letter[j]); } 

Conclusion:

 $ ./a.out hello how are youYou entered 17 characters The word is hello how are you The length of string is 17Splitting the string into chars.. 

What's happening? Why doesn't the for loop output?

Answer 1

The syntax should be:

 for (j=0; j<strlen(letter); j++) 

Since strlen is an expensive operation, and you do not change the line inside the loop, it is better to write like this:

 const int len = strlen(letter); for (j=0; j<=len; j++) 

In addition, it is strongly recommended that you always check for buffer overflows when working with C-lines and user input:

 while ((c=getchar()) != EOF && i < ARRAYSIZE - 1) 

Answer 2

Error in for, just replace the end condition and the increment as follows:

 for (j = 0; j <= strlen(letter); j++) 

Question: what is the last character?

Answer 3

for (j=0;j++;(j<=strlen(letter))) This is not true.

It should be for (j=0; j<=strlen(letter); j++) - an increment in the third position.

Answer 4

The correct for loop format is:

 for (initialization_expression; loop_condition; increment_expression){ // statements } 

so your for loop should be

 for (j = 0; j < strlen(letter); j++) 

Answer 5

In the for loop, the condition is i ++, which for the first time evaluates to false (0). You need to change them: for (j=0; j <= strlen(letter); j++)