strrev function inserts a line feed character in the first element of a string array

So basically:

#include <stdio.h>
#include <conio.h>
#include <stdlib.h>
#include <string.h>

int main(void){
    //test strrev
    char s[50];
    char s2[50];
    char *ps;
    int i=0;
    printf("String to reverse: ");
    fgets(s,50,stdin);
    ps=strrev(s);
    strcpy(s2,ps); //copy contents to a string array
    //i did the copy because using printf("%s", ps); did the same thing

    printf("Reversed string: %s\n", s2); //PECULIAR, s2 enters line feed char in s2[0]

    //test loop to determine the inserted ch开发者_如何转开发aracter
    while(1){
        if(s2[i]==10) {printf("is 10,%d", i); break;}; //the proof of LF
        if(s2[i]==12) {printf("is 12"); break;};
        if(s2[i]==13) {printf("is 13"); break;};
        if(s2[i]==15) {printf("is 15"); break;};
        i++;
    }
    for(i=0;i<50;i++){ //determine where the characters are positioned
        printf("%c: %d\n", s2[i], s2[i]);
        if(s2[i]=='\0') break;
    }

    system("PAUSE");
    return 0;
}

By running this program and entering the string....let's say "darts" will reverse the string in the array that will have the elements s2[0]='\012'=10(decimal), ...strad..., s2[7]='\0'. Is it normal for strrev to behave as such?

fgets stores the newline in the string. So when you strrev, \n (linefeed) will be the first element.

The fgets() function shall read bytes from stream into the array pointed to by s, until n-1 bytes are read, or a is read and transferred to s.

EDIT

Just tested it on Visual Studio:

char a[] = "abcd\n";
strrev(a);

printf("%d\n", a[0]); /* 10 */

strrev reverses the order of the characters in the given string. The ending null character \0 remains in place.

fgets is storing the newline in this case.

fgets stores the newline character in the char array as the last character. strrev will keep this character along with the null-terminated character (e.g. \010). ASCII 10 is newline. The string is null terminated (\0), so strrev is just taking the null-terminated char array and reversing it. If you don't want the null terminated character, then remove it. strrev reverses the order of the characters in the given string. The ending null character (\0) remains in place.