Why isn't my write method initialised? - c

Question

I have been trying to write words that are given by the user in the command shell,but for some reason my program instantly quits after the read() function,so the text in main() :"in main2\n" is never even written. I have been trying to locate my problem for about an hour now and can't seem to find it.
# include <stdio.h>
void write_zin(const char* zin,int length_zin){
const char * runner =zin;
printf("out of loop\n");
while(runner!=(runner+length_zin)){
printf("%c",*runner);
runner++;
}
}
void read(char* zin,int NUMBER_LETTERS,int NUMBER_WORDS){
int i ;
char woord[NUMBER_LETTERS+1];
zin[0]='\0';
for(i =0;i<NUMBER_WORDS;i++){
printf("Give a word with %i letters\n",NUMBER_LETTERS);
scanf("%s",woord);
strcat(zin,woord);
strcat(zin,'\0');
}
strcat(zin,'\0');
}
int main(){
const int NUMBER_LETTERS = 5;
const int NUMBER_WORDS = 2;
char zin[(NUMBER_LETTERS+1)*NUMBER_WORDS];
printf("in main 1\n");
read(zin,NUMBER_LETTERS,NUMBER_WORDS);
printf("in main 2\n");
write_zin(zin,(NUMBER_LETTERS+1)*NUMBER_WORDS);
printf("in main3\n");
return 0;
}

Answer 1

There are a couple errors in your code:
Function void read(char* zin,int NUMBER_LETTERS,int NUMBER_WORDS)
If you concatenate words separated by '\0' you will end having just one string, because every string function will stop at the first '\0' and will not process further characters. So you cannot use strcat(zin,'\0');
If you want to mark the separation between strings use another special character as '\n' The final function will be:
void read(char* zin,int NUMBER_LETTERS,int NUMBER_WORDS){
int i ;
char woord[NUMBER_LETTERS+1];
for(i =0;i<NUMBER_WORDS;i++){
printf("Give a word with %i letters\n",NUMBER_LETTERS);
scanf("%s",woord);
strcat(zin,woord);
}
}
2. Function void write_zin(const char* zin,int length_zin)
You cannot ever change the condition of a loop inside a loop. That is what you are doing, because runner is always changing inside the loop, and in addition it is part of your condition.
while(runner!=(runner+length_zin)){
printf("%c",*runner);
runner++;
}
The final function is:
void write_zin(const char* zin,int length_zin){
const char * runner =zin;
printf("out of loop");
while(*runner){
printf("'%c'",*runner);
runner++;
}
}