2025-07-25 02:15:37 +08:00
|
|
|
|
+++
|
|
|
|
|
|
title = 'C'
|
|
|
|
|
|
date = 2024-09-20T04:17:50Z
|
|
|
|
|
|
draft = false
|
2025-08-18 20:01:21 +08:00
|
|
|
|
+++
|
|
|
|
|
|
|
|
|
|
|
|
<!-- 笔试题有的时候不给正常输入，只给plain text -->
|
|
|
|
|
|
## Format Specifier
|
|
|
|
|
|
|
|
|
|
|
|
Common specifiers:
|
|
|
|
|
|
```
|
|
|
|
|
|
%d int
|
|
|
|
|
|
%u unsigned int
|
|
|
|
|
|
%c char
|
|
|
|
|
|
%s string (char s[])
|
|
|
|
|
|
%p void*
|
|
|
|
|
|
%ld long
|
|
|
|
|
|
%lld long long (64bits)
|
|
|
|
|
|
%f float/double
|
|
|
|
|
|
%lf float/double(usually used in scanf)
|
|
|
|
|
|
```
|
|
|
|
|
|
We can extend the format specifiers:
|
|
|
|
|
|
``` C
|
|
|
|
|
|
printf("%5d", 33); // width " 33"
|
|
|
|
|
|
printf("%.2f", 3.14159); // precision "3.14"
|
|
|
|
|
|
printf("%8.2f", 3.14159);// " 3.14"
|
|
|
|
|
|
printf("%-5d", 33); //Alignment "33 "
|
|
|
|
|
|
```
|
|
|
|
|
|
|
|
|
|
|
|
## IO
|
|
|
|
|
|
Read or print via terminal:
|
|
|
|
|
|
|
|
|
|
|
|
``` C
|
|
|
|
|
|
int x;
|
|
|
|
|
|
scanf("%d", &x);
|
|
|
|
|
|
printf("%d", x);
|
|
|
|
|
|
```
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
## Type Conversion
|
|
|
|
|
|
String to int, float....
|
|
|
|
|
|
``` c
|
|
|
|
|
|
int i = atoi("123");
|
|
|
|
|
|
double d = atof("3.14");
|
|
|
|
|
|
|
|
|
|
|
|
long l = strtol("123", NULL, 10); // safer, auto detec errors
|
|
|
|
|
|
double d2 = strtod("3.14", NULL);
|
|
|
|
|
|
```
|
|
|
|
|
|
|
|
|
|
|
|
Numbers to string:
|
|
|
|
|
|
``` c
|
|
|
|
|
|
int i = 123;
|
|
|
|
|
|
char buf[20];
|
|
|
|
|
|
sprintf(buf, "%d", i);
|
|
|
|
|
|
```
|
