Printing string with %s prints wrong data

Question

I'm reading from file to string with fread function and then printing the string. I defined the string as array of chars with LONGNUM size(pre defined value). I'm reading 1 element 1 byte size each time. when printing the string with : printf("the string that read is: %s\n",buffer); the output is : the string that read is b I don't get it, why in the end of the stringi get this values? when printing the string with : printf("the string that read is : %c\n",buffer[0]); I get the write output without values. please explain me why.

the code is

#include <stdio.h>
#define LONGNUM 1

void main(int argc,char *argv[])
{

    FILE * src;
    FILE * dst;
    int num;
    char buffer[LONGNUM];

    // argc is the number of the elements in argv
    // the first argv element is the name of the program

    if(argc < 3){
        printf("prototype error <source path> <dest path>\n");
        return;
    }
    printf ("source  path is : %s \n",argv[1]);
    printf ("dest path is : %s \n",argv[2]);

    src = fopen(argv[1],"r");

    while(!(feof(src))){
        num = fread(buffer,1,1,src);
        printf("the number of items read %d\n",num);
        printf("the string that read is %s\n",buffer);
        //printf("the string that read is %c\n",buffer[0]);

    }

}

I would like you to advise me what is the write way to do it. Thanks.

Answer 1

%s specifier expects null termination string. fread does not terminate string with null, so you don't see correct output. since buffer is of length 1, %c is the correct specifier to print.