C程序设计语言笔记-第一章
The C Programming language notes
一 基础变量类型、运算符和判断循环
char 字符型 character --> char c = '\n' ; [ASCII码 0-255]
short int long 整数形 interger --> int num = 120; [ unsigned 无符号表示]
float double 浮点型（单精度，双精度）--> float celsius = 12.3;
加减乘除取余， 与或非位运算， 赋值大于小于等于， if else,switch case, for do while continue break goto
二 习题代码
1.1 摄氏转华氏，华氏转摄氏以及逆序输出代码
#include <stdio.h>
#define LOWER 0 /* 下限 */
#define UPPER 300 /* 上限 */
#define STEP 20 /* 步长 */
typedef float ElementType;
void fahrToCelsius()
{
ElementType fahr, celsius;
fahr = LOWER;
// %o oct-8 | %x hex-16 | %c %s | %f %e(科学) | %d %i
printf("\nfahr to celsius:\n");
while ( fahr <= UPPER ) {
celsius = (5.0 / 9.0) * (fahr- 32.0);
// %6.2f 6个字符宽
printf("%6.2f\t%6.2f\n", fahr, celsius);
fahr = fahr + STEP;
}
}
void celsiusToFahr()
{ /* 1.4 摄氏温度转华氏 */
ElementType fahr, celsius;
celsius = UPPER;
printf("\ncelsius to fahr:\n");
for ( ; celsius >= LOWER ; celsius -= STEP ) {
fahr = (9.0 / 5.0)*celsius + 32.0;
printf("%6.2f\t%6.2f\n", celsius, fahr);
}
}
int main(int argc, char *argv[])
{
fahrToCelsius();
celsiusToFahr();
return 0;
}
1.2 标准输入输出库的单个字符获取和输出
getchar()从STDIN中获取单个字符并返回其值，如果到达文件尾则返回EOF， putchar( cha ) 将单个字符cha输出到STDOUT
printf("This is:%d\n", EOF); /* EOF define as -1 */
gets()可获取包含空格的字符串，并返回 char *指针， puts(）则将字符串输出
printf()和scanf()函数原型如下，分别以特定格式输出和获取输入
int printf( const char *format, ... );
int scanf( const char *format, ... );
字符获取输出程序如下: getchar()直到在WIndows上按下CTRL+Z产生EOF输入才停止
void getPutChar() { /* 1.5 字符输入输出 copy input to output */ int c; /* c要足够大，能存储任何getchar()的返回值 */ while ( (c = getchar())!= EOF ) { // 赋值表达式的值为赋值后左边变量的值 putchar(c); /* EOF end of file */ } }
1.3 标准输入输出库的单个字符获取和输出
统计字符流中的空白、换行和制表符
void cntSpaceTable()
{ /* 1-8 count space table and newline chars */
int c; /* big volume */
int nl, nt, ns;
nl = ns = nt = 0;
while ( (c = getchar()) != EOF ) {
if ( c == '\n' ) {
nl++;
} else if ( c == '\t' ) {
nt++;
} else if ( c == ' ' ) {
ns++;
}
}
printf("num of space, table, newline: %d, %d, %d\n"
, ns, nt, nl);
}
1-9将字符流中的多个空格替换为一个空格, 1-10将字符进行替换
void spaceChange()
{ /* 1-9 alterante mutilple sapces into one space */
int c, cs = 0; /* cs -> count space */
while ( (c = getchar()) != EOF ) {
if ( c == ' ' ) {
// print the first space, omit other space
if ( cs == 0 ) {
putchar( c );
cs++;
}
} else {
cs = 0; // 恢复计数
putchar( c );
}
}
}
void charChange()
{ /* 1-10 alterante table back and slash */
int c;
while ( (c = getchar()) != EOF ) {
switch( c ) {
case '\t': printf( "\\t" );
break;
case '\b': printf( "\\b" );
break;
case '\\': printf( "\\\\ ");
break;
default: putchar(c);
break;
}
}
printf("End\n");
}
1.4 统计单词数量
/* 1.5.4 count lines, words, and chars in input */
void countWords()
{ /* 单词计数，单词不包含空格、制表、换行符 */
int c, nl, nw, nc, state;
state = OUT;
nl = nw = nc = 0;
/* 每当遇到单词的第一个字符，就作为一个新单词计数 */
while ( (c = getchar()) != EOF ) {
++nc; /* count char */
if ( c == '\n' ) {
++nl;
}
if ( c == ' ' ||
c == '\n' ||
c == '\t' ) {
state = OUT; /* not a word */
} else if ( state == OUT ) {
state = IN;
++nw; /* start count word */
}
} /* end of while */
printf("chars:%d, lines:%d, words:%d\n", nc, nl, nw);
}
void showSingleWord()
{ /* 1-12 每个单词一行 */
int c, state;
state = OUT;
printf("Print Single Word:\n");
while ( (c = getchar()) != EOF ) {
if ( c == ' ' || c == '\n' || c == '\t' ) {
if ( state == IN ) {
printf("\n"); /* end of a word */
}
state = OUT; /* not a word */
} else if ( state == OUT ) {
state = IN; /* start count word */
}
if ( state == IN ) {
putchar(c); /* print each char of word */
}
} /* end of while */
}
1.5统计字符打印次数直方图
void printGraph( int num )
{ /* Histograph subprogram*/
int i;
for ( i = 0; i < num; i++ ) {
printf("|");
}
printf("\n");
}
void countOtherChars()
{ /* 统计数字和字母以及空格和其他字符，打印直方图 */
int c, i, nwhite ,nother;
int ndigit[10]; /* 0-9 */
int nalpha[26]; /* A-Z */
nwhite = nother = 0;
for ( i = 0; i < 26; ++i ) {
if ( i < 10) {
ndigit[i] = 0; /* init */
}
nalpha[i] = 0;
}
while ( (c = getchar()) != EOF ) {
if ( c >= '0' && c <= '9' ) {
++ndigit[c - '0'];
} else if( c >='A' && c <= 'Z' ) {
++nalpha[c - 'A']; /* upper */
} else if( c >='a' && c <= 'z' ) {
++nalpha[c - 'a']; /* lower */
}
else if ( c == ' ' || c == '\n' || c == '\t' ) {
/* space */
++nwhite;
} else {
++nother;
}
} /* end of while */
for ( i = 0; i < 10; ++i ) {
printf("%d->", i); //printf(" %d", ndigit[i]);
printGraph( ndigit[i] );
}
printf("\n ");
for ( i = 0; i < 26; ++i ) {
printf("%c->", i+'a');//printf(" %d", nalpha[i]);
printGraph( nalpha[i] );
}
printf("\nwhite space->");
printGraph(nwhite);
printf("\nother->");
printGraph(nother);
}
参考资料： 《C程序设计语言》
转载请注明：https://www.cnblogs.com/justLittleStar/p/10487055.html
