How to print a specific character from a string in C
I'm recently practicing looping. I learned how to print: for example home
to h
ho
hom
home
. by using
#include <stdio.h>
#include <string.h>
int main (){
char s[100];
printf("Input string = ");
scanf("%[^\n]", s);
for (int i=1; i<=strlen(s); i++){
for(int j = 0; j<i; j++)
printf("%c", s[j]);
printf("\n");
}
return 0;
How can i reverse it so it can be
home
hom
ho
h
instead? thank you.
It is easy to do. For example
for ( size_t i = strlen( s ); i != 0; i-- )
{
for ( size_t j = 0; j < i; j++ )
{
putchar( s[j] );
}
putchar( '\n' );
}
Another way is the following
for ( size_t i = strlen( s ); i != 0; i-- )
{
printf( ".*s\n", ( int )i, s );
}
provided that an object of the type int
is able to store the length of the passed string.
Here is a demonstration program.
#include <stdio.h>
#include <string.h>
int main( void )
{
const char *s = "home";
for (size_t i = strlen( s ); i != 0; i--)
{
printf( "%.*s\n", ( int )i, s );
}
}
The program output is
home
hom
ho
h
You could loop over the string using putc
, but it might also be helpful to understand the destructive approach that shortens the string and uses %s
to print strings. eg:
#include <stdio.h>
#include <string.h>
int
main(int argc, char **argv)
{
char *s = argc > 1 ? argv[1] : strdup("home");
for( char *e = s + strlen(s); e > s; e -= 1 ){
*e = '\0';
printf("%s\n", s);
}
return 0;
}
Note that this approach is destructive. When complete, the string is null. As an exercise, it might be helpful to fix that.