c - 字符串和字符与 printf

Question

我对以下 C 程序中 %c 和 %s 的用法感到困惑:

#include <stdio.h>
    
void main()
{
    char name[] = "siva";
    printf("%s\n", name);
    printf("%c\n", *name);
}

输出:

siva
s

为什么我们需要用指针显示一个字符%c，而一个字符串不需要指针

运行时出错

printf("%c\n", name);

我遇到了这个错误:

str.c: In function ‘main’:
str.c:9:2: warning: format ‘%c’ expects type ‘int’, but argument 2 has type ‘char *’

Answer 1

如果您尝试这样做:

#include<stdio.h>

void main()
{
 char name[]="siva";
 printf("name = %p\n", name);
 printf("&name[0] = %p\n", &name[0]);
 printf("name printed as %%s is %s\n",name);
 printf("*name = %c\n",*name);
 printf("name[0] = %c\n", name[0]);
}

输出是:

name = 0xbff5391b  
&name[0] = 0xbff5391b
name printed as %s is siva
*name = s
name[0] = s

所以'name'实际上是一个指向内存中字符数组的指针。如果您尝试读取 0xbff5391b 处的前四个字节，您将看到“s”、“i”、“v”和“a”

Location     Data
=========   ======

0xbff5391b    0x73  's'  ---> name[0]
0xbff5391c    0x69  'i'  ---> name[1]
0xbff5391d    0x76  'v'  ---> name[2]
0xbff5391e    0x61  'a'  ---> name[3]
0xbff5391f    0x00  '\0' ---> This is the NULL termination of the string

要打印一个字符，您需要将字符的值传递给 printf。该值可以引用为 name[0] 或 *name(因为对于数组 name = &name[0])。

要打印字符串，您需要将指向字符串的指针传递给 printf(在本例中为 name 或 &name[0]) .