About #define and typedef

I  wrote a simplified version function of vsprintf(char *buf, char *fmt, va_list args).

finally I found  I use "#define va_list char *"  rather than  "typedef char * va_list"

so , the following is the difference between them.

#define int_ptr int *
int_ptr a, b; // a is a pointer ,b is a int.

typedef int* int_ptr;
int_ptr a, b; //both a and b are pointer.

 

typedef int * pint ;
#define PINT int *

const pint p ;// p is unchanged ,the content that p point could be changed.
const PINT p ;//p could be changed ,the content that p point could not be changed.

 

/* SPDX-License-Identifier: GPL-2.0 */ #ifndef _LINUX_TYPES_H #define _LINUX_TYPES_H #define __EXPORTED_HEADERS__ #include <uapi/linux/types.h> #ifndef __ASSEMBLY__ #define DECLARE_BITMAP(name,bits) \ unsigned long name[BITS_TO_LONGS(bits)] typedef u32 __kernel_dev_t; typedef __kernel_fd_set fd_set; typedef __kernel_dev_t dev_t; typedef __kernel_ulong_t ino_t; typedef __kernel_mode_t mode_t; typedef unsigned short umode_t; typedef u32 nlink_t; typedef __kernel_off_t off_t; typedef __kernel_pid_t pid_t; typedef __kernel_daddr_t daddr_t; typedef __kernel_key_t key_t; typedef __kernel_suseconds_t suseconds_t; typedef __kernel_timer_t timer_t; typedef __kernel_clockid_t clockid_t; typedef __kernel_mqd_t mqd_t; typedef _Bool bool; typedef __kernel_uid32_t uid_t; typedef __kernel_gid32_t gid_t; typedef __kernel_uid16_t uid16_t; typedef __kernel_gid16_t gid16_t; typedef unsigned long uintptr_t; #ifdef CONFIG_HAVE_UID16 /* This is defined by include/asm-{arch}/posix_types.h */ typedef __kernel_old_uid_t old_uid_t; typedef __kernel_old_gid_t old_gid_t; #endif /* CONFIG_UID16 */ #if defined(__GNUC__) typedef __kernel_loff_t loff_t; #endif /* * The following typedefs are also protected by individual ifdefs for * historical reasons: */ #ifndef _SIZE_T #define _SIZE_T typedef __kernel_size_t size_t; #endif #ifndef _SSIZE_T #define _SSIZE_T typedef __kernel_ssize_t ssize_t; #endif #ifndef _PTRDIFF_T #define _PTRDIFF_T typedef __kernel_ptrdiff_t ptrdiff_t; #endif #ifndef _CLOCK_T #define _CLOCK_T typedef __kernel_clock_t clock_t; #endif #ifndef _CADDR_T #define _CADDR_T typedef __kernel_caddr_t caddr_t; #endif /* bsd */ typedef unsigned char u_char; typedef unsigned short u_short; typedef unsigned int u_int; typedef unsigned long u_long; /* sysv */ typedef unsigned char unchar; typedef unsigned short ushort; typedef unsigned int uint; typedef unsigned long ulong; #ifndef __BIT_TYPES_DEFINED__ #define __BIT_TYPES_DEFINED__ typedef u8 u_int8_t; typedef s8 int8_t; typedef u16 u_int16_t; typedef s16 int16_t; typedef u32 u_int32_t; typedef s32 int32_t; #endif /* !(__BIT_TYPES_DEFINED__) */ typedef u8 uint8_t; typedef u16 uint16_t; typedef u32 uint32_t; #if defined(__GNUC__) typedef u64 uint64_t; typedef u64 u_int64_t; typedef s64 int64_t; #endif /* this is a special 64bit data type that is 8-byte aligned */ #define aligned_u64 __aligned_u64 #define aligned_be64 __aligned_be64 #define aligned_le64 __aligned_le64 /** * The type used for indexing onto a disc or disc partition. * * Linux always considers sectors to be 512 bytes long independently * of the devices real block size. * * blkcnt_t is the type of the inode's block count. */ typedef u64 sector_t; typedef u64 blkcnt_t; /* * The type of an index into the pagecache. */ #define pgoff_t unsigned long /* * A dma_addr_t can hold any valid DMA address, i.e., any address returned * by the DMA API. * * If the DMA API only uses 32-bit addresses, dma_addr_t need only be 32 * bits wide. Bus addresses, e.g., PCI BARs, may be wider than 32 bits, * but drivers do memory-mapped I/O to ioremapped kernel virtual addresses, * so they don't care about the size of the actual bus addresses. */ #ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT typedef u64 dma_addr_t; #else typedef u32 dma_addr_t; #endif typedef unsigned int __bitwise gfp_t; typedef unsigned int __bitwise slab_flags_t; typedef unsigned int __bitwise fmode_t; #ifdef CONFIG_PHYS_ADDR_T_64BIT typedef u64 phys_addr_t; #else typedef u32 phys_addr_t; #endif typedef phys_addr_t resource_size_t; /* * This type is the placeholder for a hardware interrupt number. It has to be * big enough to enclose whatever representation is used by a given platform. */ typedef unsigned long irq_hw_number_t; typedef struct { int counter; } atomic_t; #define ATOMIC_INIT(i) { (i) } #ifdef CONFIG_64BIT typedef struct { s64 counter; } atomic64_t; #endif struct list_head { struct list_head *next, *prev; }; struct hlist_head { struct hlist_node *first; }; struct hlist_node { struct hlist_node *next, **pprev; }; struct ustat { __kernel_daddr_t f_tfree; #ifdef CONFIG_ARCH_32BIT_USTAT_F_TINODE unsigned int f_tinode; #else unsigned long f_tinode; #endif char f_fname[6]; char f_fpack[6]; }; /** * struct callback_head - callback structure for use with RCU and task_work * @next: next update requests in a list * @func: actual update function to call after the grace period. * * The struct is aligned to size of pointer. On most architectures it happens * naturally due ABI requirements, but some architectures (like CRIS) have * weird ABI and we need to ask it explicitly. * * The alignment is required to guarantee that bit 0 of @next will be * clear under normal conditions -- as long as we use call_rcu() or * call_srcu() to queue the callback. * * This guarantee is important for few reasons: * - future call_rcu_lazy() will make use of lower bits in the pointer; * - the structure shares storage space in struct page with @compound_head, * which encode PageTail() in bit 0. The guarantee is needed to avoid * false-positive PageTail(). */ struct callback_head { struct callback_head *next; void (*func)(struct callback_head *head); } __attribute__((aligned(sizeof(void *)))); #define rcu_head callback_head typedef void (*rcu_callback_t)(struct rcu_head *head); typedef void (*call_rcu_func_t)(struct rcu_head *head, rcu_callback_t func); typedef void (*swap_func_t)(void *a, void *b, int size); typedef int (*cmp_r_func_t)(const void *a, const void *b, const void *priv); typedef int (*cmp_func_t)(const void *a, const void *b); #endif /* __ASSEMBLY__ */ #endif /* _LINUX_TYPES_H */
08-09
/* Copyright (c) 2009-2017 Dave Gamble and cJSON contributors Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ /* cJSON */ /* JSON parser in C. */ /* disable warnings about old C89 functions in MSVC */ #if !defined(_CRT_SECURE_NO_DEPRECATE) && defined(_MSC_VER) #define _CRT_SECURE_NO_DEPRECATE #endif #ifdef __GNUC__ #pragma GCC visibility push(default) #endif #if defined(_MSC_VER) #pragma warning (push) /* disable warning about single line comments in system headers */ #pragma warning (disable : 4001) #endif #include <string.h> #include <stdio.h> #include <math.h> #include <stdlib.h> #include <float.h> #include <limits.h> #include <ctype.h> #ifdef ENABLE_LOCALES #include <locale.h> #endif #if defined(_MSC_VER) #pragma warning (pop) #endif #ifdef __GNUC__ #pragma GCC visibility pop #endif #include "JSON.h" /* define our own boolean type */ #define true ((cJSON_bool)1) #define false ((cJSON_bool)0) typedef struct { const unsigned char *json; size_t position; }
04-03
评论
添加红包

请填写红包祝福语或标题

红包个数最小为10个

红包金额最低5元

当前余额3.43前往充值 >
需支付:10.00
成就一亿技术人!
领取后你会自动成为博主和红包主的粉丝 规则
hope_wisdom
发出的红包
实付
使用余额支付
点击重新获取
扫码支付
钱包余额 0

抵扣说明:

1.余额是钱包充值的虚拟货币,按照1:1的比例进行支付金额的抵扣。
2.余额无法直接购买下载,可以购买VIP、付费专栏及课程。

余额充值