今日份C语言做题——每天都有新收获
今日份C语言做题——每天都有新收获
目录- 今日份C语言做题——每天都有新收获
- 做几道题
- 1.打印图形
- 2.近似求PI
- 3.打印图形
- 4.分段函数
- 每天多思考一点点
- 补充知识ascii码表，
- 做几道题
做几道题
1.打印图形
#include
int main() {
char t;
int num;
scanf("%d %c", &num, &t);
for (int i = 0; i < 2 * num - 1; i++) {//分行
char c = t;
for (int j = 0; j < 2 * num - 1; j++) {//分列
if (c > 'z') { //实现首尾相连
c = c - 'z' + 'a' ;
}
if (c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u') { //实现排除元音
c++;
}
if (i < num - 1 ) {
if (j == i) {//这种先输出整体再掩盖的方法值得我们去认真反思
printf("%c", c);
} else if (j == 2 * num - 2 - i) {
printf("%c\n", c);
} else if (j < 2 * num - 1 - i) {
printf(" ");
}
} else {
if (j == i) {
printf("%c\n", c);
} else if (j == 2 * num - 2 - i) {
printf("%c", c);
} else if (j < i) {
printf(" ");
}
}
c++;
}
}
}
做题总结：可以先一步一步来，把整个文字图形先打出，最后只需要控制输出就可以了；
2.近似求PI
使用格里高利公式求π的近似值，要求最后一项的绝对值精确到从键盘读入的数。（比如0.01,0.001,0.0001等）(PI/4=1-1/3+1/5-1/7+....)
#include
#include
int main(){
double accuracy=0;
scanf("%lf",&accuracy);
double sum=0,flag=1,item=1,denominator = 1;
while(fabs(4*item)>accuracy){
sum+=4*item;
denominator +=2;
flag=-flag;
item=flag/denominator ;
}
double pi=sum;
printf("%.4lf\n",pi);
}
总结：
-
这里有个比较可疑的地方：在作者自己的终端上要等好一段时间才能输入东西；
-
需要注意的地方是上面的精度比较，这是一种小套路，前一个数和后一个数的差值绝对值与精度比较；
3.打印图形
50
ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWX
Y
Z
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
UVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQR
#include
char* condition(char* c){
if(*c>'Z'){
*c=*c-'Z'+'A'-1;
}
return c;
}
int main() {
int num;
char c = 'A';
scanf("%d", &num);
for (int i = 0; i < num; i++) {
if (i == 0 || i == num - 1) {
for (int j = 0; j < num; j++) {
printf("%c", *condition(&c));
c++;
}
printf("\n");
} else {
for (int k = 0; k < num - 1-i; k++) {
printf(" ");
}
printf("%c\n", *condition(&c));
c++;
}
}
}
4.分段函数
#include
#include
double f(double x){
double ret=0;
if(x<0){
ret=pow(2,x)+1;
}else if(x<5){
ret=sqrt(x+4);
}else if(x<16){
ret=-1/(x-16)+32.0/11;
}
return ret;
}
int main(){
double x;
scanf("%lf",&x);
if(x>=16){
printf("Jaanai tcl!\n");
}else{
printf("%.2lf\n",f(x));
}
}
每天多思考一点点
-
探究gets机制
#include#include int main() { char s1[10]; gets(s1); puts(s1); } 执行步骤 调试时s1中显示的内存 0 s1 = "\000\000D\000\000\000,/\252" 1（2dasd\03） s1 = "2dasd\\03\000" 2（puts后） s1 = "2dasd\\03\000" - 背景知识补充：
printf("ohhhhhh\000hhhh");上面的输出是ohhhhhh，说明\000起到的作用就是\0的意思，不过是在八进制下表示而已；
-
回到原来的"\000\000D\000\000\000,/\252"发现最多也只有九个字符表示成字符分别是'\0' , '\0' , 'D' , '\0' , '\0' , '\0' , ',' , '/' , 'a' (其中\252所对应的'a'在终端显示不出来)但我们指导其实调试中显示的也不准确，最末尾应该还有一个'\0',一共10个元素，证明如下；
#include#include int main() { char s1[3]; printf("%u\n",sizeof(s1)/sizeof(s1[0])); printf("%d\n",strlen(s1)); } 3 2 -
所以就是说gets对终端输入的字符数并没有限制，而且还会在末尾自动添'\0'做结尾；
补充知识ascii码表，
其中decimal为十进制，octal为八进制，hexadecimal为十六进制，binary为二进制
DEC OCT HEX BIN 缩写/符号 HTML实体 描述 0 000 00 00000000 NUL ? Null char (空字符) 1 001 01 00000001 SOH ? Start of Heading (标题开始) 2 002 02 00000010 STX ? Start of Text (正文开始) 3 003 03 00000011 ETX ? End of Text (正文结束) 4 004 04 00000100 EOT ? End of Transmission (传输结束) 5 005 05 00000101 ENQ ? Enquiry (请求) 6 006 06 00000110 ACK ? Acknowledgment (收到通知) 7 007 07 00000111 BEL ? Bell (响铃) 8 010 08 00001000 BS ? Back Space (退格) 9 011 09 00001001 HT Horizontal Tab (水平制表符) 10 012 0A 00001010 LF Line Feed (换行键) 11 013 0B 00001011 VT ? Vertical Tab (垂直制表符) 12 014 0C 00001100 FF Form Feed (换页键) 13 015 0D 00001101 CR Carriage Return (回车键) 14 016 0E 00001110 SO ? Shift Out / X-On (不用切换) 15 017 0F 00001111 SI ? Shift In / X-Off (启用切换) 16 020 10 00010000 DLE ? Data Line Escape (数据链路转义) 17 021 11 00010001 DC1 ? Device Control 1 (设备控制1) 18 022 12 00010010 DC2 ? Device Control 2 (设备控制2) 19 023 13 00010011 DC3 ? Device Control 3 (设备控制3) 20 024 14 00010100 DC4 ? Device Control 4 (设备控制4) 21 025 15 00010101 NAK ? Negative Acknowledgement (拒绝接收) 22 026 16 00010110 SYN ? Synchronous Idle (同步空闲) 23 027 17 00010111 ETB ? End of Transmit Block (传输块结束) 24 030 18 00011000 CAN ? Cancel (取消) 25 031 19 00011001 EM ? End of Medium (介质中断) 26 032 1A 00011010 SUB ? Substitute (替补) 27 033 1B 00011011 ESC ? Escape (溢出) 28 034 1C 00011100 FS ? File Separator (文件分割符) 29 035 1D 00011101 GS ? Group Separator (分组符) 30 036 1E 00011110 RS ? Record Separator (记录分离符) 31 037 1F 00011111 US ? Unit Separator (单元分隔符) 32 040 20 00100000 Space (空格) 33 041 21 00100001 ! ! Exclamation mark 34 042 22 00100010 " " Double quotes 35 043 23 00100011 # # Number 36 044 24 00100100 $ $ Dollar 37 045 25 00100101 % % Procenttecken 38 046 26 00100110 & & Ampersand 39 047 27 00100111 ' ' Single quote 40 050 28 00101000 ( ( Open parenthesis 41 051 29 00101001 ) ) Close parenthesis 42 052 2A 00101010 * * Asterisk 43 053 2B 00101011 + + Plus 44 054 2C 00101100 , , Comma 45 055 2D 00101101 - - Hyphen 46 056 2E 00101110 . . Period, dot or full stop 47 057 2F 00101111 / / Slash or divide 48 060 30 00110000 0 0 Zero 49 061 31 00110001 1 1 One 50 062 32 00110010 2 2 Two 51 063 33 00110011 3 3 Three 52 064 34 00110100 4 4 Four 53 065 35 00110101 5 5 Five 54 066 36 00110110 6 6 Six 55 067 37 00110111 7 7 Seven 56 070 38 00111000 8 8 Eight 57 071 39 00111001 9 9 Nine 58 072 3A 00111010 : : Colon 59 073 3B 00111011 ; ; Semicolon 60 074 3C 00111100 < < Less than 61 075 3D 00111101 = = Equals 62 076 3E 00111110 > > Greater than 63 077 3F 00111111 ? ? Question mark 64 100 40 01000000 @ @ At symbol 65 101 41 01000001 A A Uppercase A 66 102 42 01000010 B B Uppercase B 67 103 43 01000011 C C Uppercase C 68 104 44 01000100 D D Uppercase D 69 105 45 01000101 E E Uppercase E 70 106 46 01000110 F F Uppercase F 71 107 47 01000111 G G Uppercase G 72 110 48 01001000 H H Uppercase H 73 111 49 01001001 I I Uppercase I 74 112 4A 01001010 J J Uppercase J 75 113 4B 01001011 K K Uppercase K 76 114 4C 01001100 L L Uppercase L 77 115 4D 01001101 M M Uppercase M 78 116 4E 01001110 N N Uppercase N 79 117 4F 01001111 O O Uppercase O 80 120 50 01010000 P P Uppercase P 81 121 51 01010001 Q Q Uppercase Q 82 122 52 01010010 R R Uppercase R 83 123 53 01010011 S S Uppercase S 84 124 54 01010100 T T Uppercase T 85 125 55 01010101 U U Uppercase U 86 126 56 01010110 V V Uppercase V 87 127 57 01010111 W W Uppercase W 88 130 58 01011000 X X Uppercase X 89 131 59 01011001 Y Y Uppercase Y 90 132 5A 01011010 Z Z Uppercase Z 91 133 5B 01011011 [ [ Opening bracket 92 134 5C 01011100 \ \ Backslash 93 135 5D 01011101 ] ] Closing bracket 94 136 5E 01011110 ^ ^ Caret - circumflex 95 137 5F 01011111 _ _ Underscore 96 140 60 01100000 ` ` Grave accent 97 141 61 01100001 a a Lowercase a 98 142 62 01100010 b b Lowercase b 99 143 63 01100011 c c Lowercase c 100 144 64 01100100 d d Lowercase d 101 145 65 01100101 e e Lowercase e 102 146 66 01100110 f f Lowercase f 103 147 67 01100111 g g Lowercase g 104 150 68 01101000 h h Lowercase h 105 151 69 01101001 i i Lowercase i 106 152 6A 01101010 j j Lowercase j 107 153 6B 01101011 k k Lowercase k 108 154 6C 01101100 l l Lowercase l 109 155 6D 01101101 m m Lowercase m 110 156 6E 01101110 n n Lowercase n 111 157 6F 01101111 o o Lowercase o 112 160 70 01110000 p p Lowercase p 113 161 71 01110001 q q Lowercase q 114 162 72 01110010 r r Lowercase r 115 163 73 01110011 s s Lowercase s 116 164 74 01110100 t t Lowercase t 117 165 75 01110101 u u Lowercase u 118 166 76 01110110 v v Lowercase v 119 167 77 01110111 w w Lowercase w 120 170 78 01111000 x x Lowercase x 121 171 79 01111001 y y Lowercase y 122 172 7A 01111010 z z Lowercase z 123 173 7B 01111011 { { Opening brace 124 174 7C 01111100 | | Vertical bar 125 175 7D 01111101 } } Closing brace 126 176 7E 01111110 ~ ~ Equivalency sign (tilde) 127 177 7F 01111111 ? Delete DEC OCT HEX BIN 缩写/符号 HTML实体 描述 128 200 80 10000000 € ? Euro sign 129 201 81 10000001 130 202 82 10000010 ? ? Single low-9 quotation mark 131 203 83 10000011 ? ? Latin small letter f with hook 132 204 84 10000100 ? ? Double low-9 quotation mark 133 205 85 10000101 … ? Horizontal ellipsis 134 206 86 10000110 ? ? Dagger 135 207 87 10000111 ? ? Double dagger 136 210 88 10001000 ? ? Modifier letter circumflex accent 137 211 89 10001001 ‰ ? Per mille sign 138 212 8A 10001010 ? ? Latin capital letter S with caron 139 213 8B 10001011 ? ? Single left-pointing angle quotation 140 214 8C 10001100 ? ? Latin capital ligature OE 141 215 8D 10001101 142 216 8E 10001110 ? ? Latin capital letter Z with caron 143 217 8F 10001111 144 220 90 10010000 145 221 91 10010001 ‘ ? Left single quotation mark 146 222 92 10010010 ’ ? Right single quotation mark 147 223 93 10010011 “ ? Left double quotation mark 148 224 94 10010100 ” ? Right double quotation mark 149 225 95 10010101 ? ? Bullet 150 226 96 10010110 – ? En dash 151 227 97 10010111 — ? Em dash 152 230 98 10011000 ? ? Small tilde 153 231 99 10011001 ? ? Trade mark sign 154 232 9A 10011010 ? ? Latin small letter S with caron 155 233 9B 10011011 ? ? Single right-pointing angle quotation mark 156 234 9C 10011100 ? ? Latin small ligature oe 157 235 9D 10011101 158 236 9E 10011110 ? ? Latin small letter z with caron 159 237 9F 10011111 ? ? Latin capital letter Y with diaeresis 160 240 A0 10100000 Non-breaking space 161 241 A1 10100001 ? ? Inverted exclamation mark 162 242 A2 10100010 ￠ ￠ Cent sign 163 243 A3 10100011 ￡ ￡ Pound sign 164 244 A4 10100100 ¤ ¤ Currency sign 165 245 A5 10100101 ￥ ￥ Yen sign 166 246 A6 10100110 | | Pipe, Broken vertical bar 167 247 A7 10100111 § § Section sign 168 250 A8 10101000 ¨ ¨ Spacing diaeresis - umlaut 169 251 A9 10101001 ? ? Copyright sign 170 252 AA 10101010 a a Feminine ordinal indicator 171 253 AB 10101011 ? ? Left double angle quotes 172 254 AC 10101100 ? ? Not sign 173 255 AD 10101101 - - Soft hyphen 174 256 AE 10101110 ? ? Registered trade mark sign 175 257 AF 10101111 ˉ ˉ Spacing macron - overline 176 260 B0 10110000 ° ° Degree sign 177 261 B1 10110001 ± ± Plus-or-minus sign 178 262 B2 10110010 2 2 Superscript two - squared 179 263 B3 10110011 3 3 Superscript three - cubed 180 264 B4 10110100 ′ ′ Acute accent - spacing acute 181 265 B5 10110101 μ μ Micro sign 182 266 B6 10110110 ? ? Pilcrow sign - paragraph sign 183 267 B7 10110111 · · Middle dot - Georgian comma 184 270 B8 10111000 ? ? Spacing cedilla 185 271 B9 10111001 1 1 Superscript one 186 272 BA 10111010 o o Masculine ordinal indicator 187 273 BB 10111011 ? ? Right double angle quotes 188 274 BC 10111100 ? ? Fraction one quarter 189 275 BD 10111101 ? ? Fraction one half 190 276 BE 10111110 ? ? Fraction three quarters 191 277 BF 10111111 ? ? Inverted question mark 192 300 C0 11000000 à à Latin capital letter A with grave 193 301 C1 11000001 á á Latin capital letter A with acute 194 302 C2 11000010 ? ? Latin capital letter A with circumflex 195 303 C3 11000011 ? ? Latin capital letter A with tilde 196 304 C4 11000100 ? ? Latin capital letter A with diaeresis 197 305 C5 11000101 ? ? Latin capital letter A with ring above 198 306 C6 11000110 ? ? Latin capital letter AE 199 307 C7 11000111 ? ? Latin capital letter C with cedilla 200 310 C8 11001000 è è Latin capital letter E with grave 201 311 C9 11001001 é é Latin capital letter E with acute 202 312 CA 11001010 ê ê Latin capital letter E with circumflex 203 313 CB 11001011 ? ? Latin capital letter E with diaeresis 204 314 CC 11001100 ì ì Latin capital letter I with grave 205 315 CD 11001101 í í Latin capital letter I with acute 206 316 CE 11001110 ? ? Latin capital letter I with circumflex 207 317 CF 11001111 ? ? Latin capital letter I with diaeresis 208 320 D0 11010000 D D Latin capital letter ETH 209 321 D1 11010001 ? ? Latin capital letter N with tilde 210 322 D2 11010010 ò ò Latin capital letter O with grave 211 323 D3 11010011 ó ó Latin capital letter O with acute 212 324 D4 11010100 ? ? Latin capital letter O with circumflex 213 325 D5 11010101 ? ? Latin capital letter O with tilde 214 326 D6 11010110 ? ? Latin capital letter O with diaeresis 215 327 D7 11010111 × × Multiplication sign 216 330 D8 11011000 ? ? Latin capital letter O with slash 217 331 D9 11011001 ù ù Latin capital letter U with grave 218 332 DA 11011010 ú ú Latin capital letter U with acute 219 333 DB 11011011 ? ? Latin capital letter U with circumflex 220 334 DC 11011100 ü ü Latin capital letter U with diaeresis 221 335 DD 11011101 Y Y Latin capital letter Y with acute 222 336 DE 11011110 T T Latin capital letter THORN 223 337 DF 11011111 ? ? Latin small letter sharp s - ess-zed 224 340 E0 11100000 à à Latin small letter a with grave 225 341 E1 11100001 á á Latin small letter a with acute 226 342 E2 11100010 a a Latin small letter a with circumflex 227 343 E3 11100011 ? ? Latin small letter a with tilde 228 344 E4 11100100 ? ? Latin small letter a with diaeresis 229 345 E5 11100101 ? ? Latin small letter a with ring above 230 346 E6 11100110 ? ? Latin small letter ae 231 347 E7 11100111 ? ? Latin small letter c with cedilla 232 350 E8 11101000 è è Latin small letter e with grave 233 351 E9 11101001 é é Latin small letter e with acute 234 352 EA 11101010 ê ê Latin small letter e with circumflex 235 353 EB 11101011 ? ? Latin small letter e with diaeresis 236 354 EC 11101100 ì ì Latin small letter i with grave 237 355 ED 11101101 í í Latin small letter i with acute 238 356 EE 11101110 ? ? Latin small letter i with circumflex 239 357 EF 11101111 ? ? Latin small letter i with diaeresis 240 360 F0 11110000 e e Latin small letter eth 241 361 F1 11110001 ? ? Latin small letter n with tilde 242 362 F2 11110010 ò ò Latin small letter o with grave 243 363 F3 11110011 ó ó Latin small letter o with acute 244 364 F4 11110100 ? ? Latin small letter o with circumflex 245 365 F5 11110101 ? ? Latin small letter o with tilde 246 366 F6 11110110 ? ? Latin small letter o with diaeresis 247 367 F7 11110111 ÷ ÷ Division sign 248 370 F8 11111000 ? ? Latin small letter o with slash 249 371 F9 11111001 ù ù Latin small letter u with grave 250 372 FA 11111010 ú ú Latin small letter u with acute 251 373 FB 11111011 ? ? Latin small letter u with circumflex 252 374 FC 11111100 ü ü Latin small letter u with diaeresis 253 375 FD 11111101 y y Latin small letter y with acute 254 376 FE 11111110 t t Latin small letter thorn 255 377 FF 11111111 ? ? Latin small letter y with diaeresis