我觉得这是一个送分题，奈何知乎人才太多了，给出了各种古怪的写法，如果是做项目的话，我比骄建议一些正常的写法，就是大家都能看得懂的，不要搞什么花里胡哨，不过你要是交流的话，既然是交流，我不觉得要多正规，即使你的观点有问题，我觉得也可以拿出来说说，毕竟是交流，各抒己见，发表自己的观点是最重要的。

---- 为什么不建议大家花里胡哨

我觉得花里胡哨之前首先是你基础非常好了再去花里胡哨，不要自己很多基础的东西还搞不清楚就去花里胡哨。

---- 看这个代码，题外话

看看基础搞不明白的杀伤有多大。

void start_f(int first_start)
{char time_buf[512];char buf[512];if(!first_start){sprintf(time_buf,"%s",get_time());int len = strlen(time_buf);time_buf[len -1 ] = 0;printf("time_buf:%s\n",time_buf);}
}

这个是在网上看到的一个代码，比较典型的基础不牢靠，对strlen 理解不够。

常规解题代码

我觉得对于这个题目，使用for是非常常规的思考方式，所以我看了所有的回答之后，写了一个常规的代码。

---- 代码如下

#include "stdio.h"void main(void)
{int i=0;for(i=1;i<=100;i++){printf("%d ",i);}for(i=99;i>=1;i--){printf("%d ",i);}
}

---- 代码输出

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 99 98 97 96 95 94 93 92 91 90 89 88 87 86 85 84 83 82 81 80 79 78 77 76 75 74 73 72 71 70 69 68 67 66 65 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
--------------------------------
Process exited after 0.04664 seconds with return value 2
请按任意键继续. . .

---- 为什么是 void main ，而不是Int main ，题外话

这个是一个知乎留言提到的，很多人也对这个有疑惑，main 的写法有几种，有的被认为是正规的，有的被认为是不正规的。

main是一个函数，既然是一个函数，就遵从函数的规则就好。

所以，这样写输出并没有什么问题

#include <stdio.h>char * main()
{printf("hhh\n"); return (char * )NULL;
}

我们还要知道比较常见的几种

int main(int argc,char **argv){}
int main(int argc,char *argv[]){}
int main(void){}

---对于返回值的认知

main 函数是被操作系统调用的，既然是被操作系统调用的，操作系统会判断函数的返回值，通过返回值来判断程序是否正确运行，所以main函数的返回值是有意义的，我示例中的写法并不规范。

对main的解读

比较玄乎的写法

#include "stdio.h"
void fun(int n)
{if(n<100){printf("%d ",n); fun(n+1);} printf("%d ",n);
}int main(void)
{fun(1);return 0;
}

---- 程序输出

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 99 98 97 96 95 94 93 92 91 90 89 88 87 86 85 84 83 82 81 80 79 78 77 76 75 74 73 72 71 70 69 68 67 66 65 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
--------------------------------
Process exited after 0.05336 seconds with return value 0
请按任意键继续. . .

这里涉及到递归，如果没有这个概念的人，脑子可能弯不过来

大概是这样执行顺序的

fun(1)
->fun(2)
--->fun(3)
........
---->fun(99)

---- 把上面的代码修改下

#include "stdio.h"
void fun(int n)
{if(n<100){printf("fun(%d) ",n); fun(n+1);} printf("fun(%d) ",n);
}int main(void)
{fun(1);return 0;
}

---- 代码输出

fun(1) fun(2) fun(3) fun(4) fun(5) fun(6) fun(7) fun(8) fun(9) fun(10) fun(11) fun(12) fun(13) fun(14) fun(15) fun(16) fun(17) fun(18) fun(19) fun(20) fun(21) fun(22) fun(23) fun(24) fun(25) fun(26) fun(27) fun(28) fun(29) fun(30) fun(31) fun(32) fun(33) fun(34) fun(35) fun(36) fun(37) fun(38) fun(39) fun(40) fun(41) fun(42) fun(43) fun(44) fun(45) fun(46) fun(47) fun(48) fun(49) fun(50) fun(51) fun(52) fun(53) fun(54) fun(55) fun(56) fun(57) fun(58) fun(59) fun(60) fun(61) fun(62) fun(63) fun(64) fun(65) fun(66) fun(67) fun(68) fun(69) fun(70) fun(71) fun(72) fun(73) fun(74) fun(75) fun(76) fun(77) fun(78) fun(79) fun(80) fun(81) fun(82) fun(83) fun(84) fun(85) fun(86) fun(87) fun(88) fun(89) fun(90) fun(91) fun(92) fun(93) fun(94) fun(95) fun(96) fun(97) fun(98) fun(99) fun(100) fun(99) fun(98) fun(97) fun(96) fun(95) fun(94) fun(93) fun(92) fun(91) fun(90) fun(89) fun(88) fun(87) fun(86) fun(85) fun(84) fun(83) fun(82) fun(81) fun(80) fun(79) fun(78) fun(77) fun(76) fun(75) fun(74) fun(73) fun(72) fun(71) fun(70) fun(69) fun(68) fun(67) fun(66) fun(65) fun(64) fun(63) fun(62) fun(61) fun(60) fun(59) fun(58) fun(57) fun(56) fun(55) fun(54) fun(53) fun(52) fun(51) fun(50) fun(49) fun(48) fun(47) fun(46) fun(45) fun(44) fun(43) fun(42) fun(41) fun(40) fun(39) fun(38) fun(37) fun(36) fun(35) fun(34) fun(33) fun(32) fun(31) fun(30) fun(29) fun(28) fun(27) fun(26) fun(25) fun(24) fun(23) fun(22) fun(21) fun(20) fun(19) fun(18) fun(17) fun(16) fun(15) fun(14) fun(13) fun(12) fun(11) fun(10) fun(9) fun(8) fun(7) fun(6) fun(5) fun(4) fun(3) fun(2) fun(1)

重点在于只有if 判断为假后，才结束递归，但是递归不能无限大，太大了会撑爆栈空间的哦

递归的文章

C 语言，你真的懂递归了吗？

比如这样

再看看一个高赞的奇葩写法

作者：已注销了
链接：https://www.zhihu.com/question/420856018/answer/1474402510
来源：知乎
著作权归作者所有。商业转载请联系作者获得授权，非商业转载请注明出处。#include <stdio.h>
int main() {printf("1");printf(" ");printf("2");printf(" ");printf("3");printf(" ");printf("4");printf(" ");printf("5");printf(" ");printf("6");printf(" ");printf("7");printf(" ");printf("8");printf(" ");printf("9");printf(" ");printf("10");printf(" ");printf("11");printf(" ");printf("12");printf(" ");printf("13");printf(" ");printf("14");printf(" ");printf("15");printf(" ");printf("16");printf(" ");printf("17");printf(" ");printf("18");printf(" ");printf("19");printf(" ");printf("20");printf(" ");printf("21");printf(" ");printf("22");printf(" ");printf("23");printf(" ");printf("24");printf(" ");printf("25");printf(" ");printf("26");printf(" ");printf("27");printf(" ");printf("28");printf(" ");printf("29");printf(" ");printf("30");printf(" ");printf("31");printf(" ");printf("32");printf(" ");printf("33");printf(" ");printf("34");printf(" ");printf("35");printf(" ");printf("36");printf(" ");printf("37");printf(" ");printf("38");printf(" ");printf("39");printf(" ");printf("40");printf(" ");printf("41");printf(" ");printf("42");printf(" ");printf("43");printf(" ");printf("44");printf(" ");printf("45");printf(" ");printf("46");printf(" ");printf("47");printf(" ");printf("48");printf(" ");printf("49");printf(" ");printf("50");printf(" ");printf("51");printf(" ");printf("52");printf(" ");printf("53");printf(" ");printf("54");printf(" ");printf("55");printf(" ");printf("56");printf(" ");printf("57");printf(" ");printf("58");printf(" ");printf("59");printf(" ");printf("60");printf(" ");printf("61");printf(" ");printf("62");printf(" ");printf("63");printf(" ");printf("64");printf(" ");printf("65");printf(" ");printf("66");printf(" ");printf("67");printf(" ");printf("68");printf(" ");printf("69");printf(" ");printf("70");printf(" ");printf("71");printf(" ");printf("72");printf(" ");printf("73");printf(" ");printf("74");printf(" ");printf("75");printf(" ");printf("76");printf(" ");printf("77");printf(" ");printf("78");printf(" ");printf("79");printf(" ");printf("80");printf(" ");printf("81");printf(" ");printf("82");printf(" ");printf("83");printf(" ");printf("84");printf(" ");printf("85");printf(" ");printf("86");printf(" ");printf("87");printf(" ");printf("88");printf(" ");printf("89");printf(" ");printf("90");printf(" ");printf("91");printf(" ");printf("92");printf(" ");printf("93");printf(" ");printf("94");printf(" ");printf("95");printf(" ");printf("96");printf(" ");printf("97");printf(" ");printf("98");printf(" ");printf("99");printf(" ");printf("100");printf(" ");printf("99");printf(" ");printf("98");printf(" ");printf("97");printf(" ");printf("96");printf(" ");printf("95");printf(" ");printf("94");printf(" ");printf("93");printf(" ");printf("92");printf(" ");printf("91");printf(" ");printf("90");printf(" ");printf("89");printf(" ");printf("88");printf(" ");printf("87");printf(" ");printf("86");printf(" ");printf("85");printf(" ");printf("84");printf(" ");printf("83");printf(" ");printf("82");printf(" ");printf("81");printf(" ");printf("80");printf(" ");printf("79");printf(" ");printf("78");printf(" ");printf("77");printf(" ");printf("76");printf(" ");printf("75");printf(" ");printf("74");printf(" ");printf("73");printf(" ");printf("72");printf(" ");printf("71");printf(" ");printf("70");printf(" ");printf("69");printf(" ");printf("68");printf(" ");printf("67");printf(" ");printf("66");printf(" ");printf("65");printf(" ");printf("64");printf(" ");printf("63");printf(" ");printf("62");printf(" ");printf("61");printf(" ");printf("60");printf(" ");printf("59");printf(" ");printf("58");printf(" ");printf("57");printf(" ");printf("56");printf(" ");printf("55");printf(" ");printf("54");printf(" ");printf("53");printf(" ");printf("52");printf(" ");printf("51");printf(" ");printf("50");printf(" ");printf("49");printf(" ");printf("48");printf(" ");printf("47");printf(" ");printf("46");printf(" ");printf("45");printf(" ");printf("44");printf(" ");printf("43");printf(" ");printf("42");printf(" ");printf("41");printf(" ");printf("40");printf(" ");printf("39");printf(" ");printf("38");printf(" ");printf("37");printf(" ");printf("36");printf(" ");printf("35");printf(" ");printf("34");printf(" ");printf("33");printf(" ");printf("32");printf(" ");printf("31");printf(" ");printf("30");printf(" ");printf("29");printf(" ");printf("28");printf(" ");printf("27");printf(" ");printf("26");printf(" ");printf("25");printf(" ");printf("24");printf(" ");printf("23");printf(" ");printf("22");printf(" ");printf("21");printf(" ");printf("20");printf(" ");printf("19");printf(" ");printf("18");printf(" ");printf("17");printf(" ");printf("16");printf(" ");printf("15");printf(" ");printf("14");printf(" ");printf("13");printf(" ");printf("12");printf(" ");printf("11");printf(" ");printf("10");printf(" ");printf("9");printf(" ");printf("8");printf(" ");printf("7");printf(" ");printf("6");printf(" ");printf("5");printf(" ");printf("4");printf(" ");printf("3");printf(" ");printf("2");printf(" ");printf("1");printf(" ");return 0;
}

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