Simplify file descriptor handling

README.md

@@ -179,7 +179,7 @@ This feature can be utilized for tests involving the emulator, such as compiler
 You can also combine this option with `-q` to directly use the output.
 For example, if you want to read the register x10 (a0), then run the following command:
 ```shell
-$ build/rv32emu -d - out.elf -q | jq .x10
+$ build/rv32emu -d - -q out.elf | jq .x10
 ```
 
 ## RISC-V Instructions/Registers Usage Statistics

src/emulate.c

@@ -1038,13 +1038,7 @@ void ecall_handler(riscv_t *rv)
 
 void dump_registers(riscv_t *rv, char *out_file_path)
 {
-    FILE *f;
-    if (!strncmp(out_file_path, "-", 1)) {
-        f = stdout;
-    } else {
-        f = fopen(out_file_path, "w");
-    }
-
+    FILE *f = out_file_path[0] == '-' ? stdout : fopen(out_file_path, "w");
     if (!f) {
         fprintf(stderr, "Cannot open registers output file.\n");
         return;