加载 C 不正确

Question

Below is my simple code, in which I am trying to make a loading animation, but the output seems to be unrelated to what is expected. Please assist me in pointing out my mistakes, as I am new to C.

#include <stdio.h>
#include <windows.h>

LO();
main(){
    LO();
}

LO(){
    char ad = '-';
    int n   = 1;
    while (n<10){
        printf(" %c >", ad);
        Sleep(1000);
        ad += n*'-';
        n++;
    }
}

The output:

 - > Z > ┤ > ; > ∩ > ╨ > ▐ >  > ü >

What I expected:

->

then clear screen

-->

then clear screen

--->

and more till a certain times.

then clear screen

Answer 1

C is not Python. It does not have n * string concatenation.

This line:

ad += n*'-';

ad has a numeric ASCII value of 45 at first. The literal '-' is also 45. You expect that you concatenate n * '-' to the string but you are just doing numeric calculations.

So when n == 1 you add 45 to 45 which is ASCII 'Z', and that's what you see in your output.

When you want to concatenate in C you use strcpy , strcat .

A rather hacky way to do this would be the %.*s format specifier for printf.

const char *fullline = "---------------------------------";
for (int i = 1; i < 10; i++)
    printf("%.*s\n", i, fullline);

printf cuts off fullline after i characters.

Answer 2

One approach would be to use a for loop:

void LO(void)
{
    int n = 1;

    while(n < 10)
    {
        for(int i = 0; i < n; i++)
            printf("-");
        printf(">");

        Sleep(1000);

        printf("\r");
        fflush(stdout);

        n++;
    }
}