why can not use strcat() in below c code?

[nilushika]

when I try to run this it throws a runtime error.

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
void savefile(char *p);
int main(){	
savefile("c proramming"); 
}
void savefile(char *p){
  	FILE*fp;
	fp=fopen("result.txt","w");
	if(fp==NULL){
		printf("error");
		exit(0);
	}
	strcat(p,"\n");//line A
	fputs(p,fp);
	fclose(fp);
}

but when i commented line A it runs.can't understand what is going wrong there.can you please help me?

[weaknessforcats]

You are using "c proramming" as your string to append to. This is a literal and is fixed in size. That is, it is a constant.

You need to pass your function the address of a string that has a \0 already in it. A string you have created yourself.

char str[100];
strcpy(str,"c proramming"); 
savefile(str);