The C programming language (second edition,KR) exercise(CHAPTER 7)
E x c e r c i s e 7 − 1 Excercise\quad 7-1 Excercise7−1:
#include <stdio.h>
#include <string.h>
#include <ctype.h>enum type { LOWER, UPPER };int main(int argc, char *argv[])
{int c, mode = -1;if (stricmp(*argv, "lower.exe") == 0) {printf("To lower\n");mode = LOWER; }else if (stricmp(*argv, "upper.exe") == 0) {printf("To upper\n");mode = UPPER; } if (mode == LOWER){while ((c = getchar()) != EOF)putchar(tolower(c)); }else if (mode == UPPER){while ((c = getchar()) != EOF)putchar(toupper(c)); }return 0;
}
E x c e r c i s e 7 − 2 Excercise\quad 7-2 Excercise7−2:
#include <stdio.h>
#include <ctype.h>/* "%x" for hex, "%o" for octal */
#define FORMAT "%x"
#define LINELEN 75int main()
{int c, i = 0;while ((c = getchar()) != EOF){/* reset line length counter */ if (c == '\n') i = 0;/* check if equal to line length. If so, print new line and reset counter */ else if (++i == LINELEN) {i = 0;putchar('\n');}/* graphic characters and spaces */ if (isgraph(c) || isspace(c)) {putchar(c); }else{/* non-graphic characters */printf(FORMAT, c); }}return 0;
}
E x c e r c i s e 7 − 3 Excercise\quad 7-3 Excercise7−3:
#include <stdio.h>
#include <stdarg.h>void minprintf(char *fmt, ...);int main()
{char *sval = "10";int ival = 11;double dval = 12.13;unsigned int uival = 14;char cval = 'F';void *pval = sval;minprintf("%%s=%s, %%d=%d, %%i=%i, %%f=%f, %%e=%e, %%E=%E, %%g=%g, %%G=%G, %%o=%o, %%x=%x\n", sval, ival, ival, dval, dval, dval, dval, dval, uival, uival);printf("%%s=%s, %%d=%d, %%i=%i, %%f=%f, %%e=%e, %%E=%E, %%g=%g, %%G=%G, %%o=%o, %%x=%x\n", sval, ival, ival, dval, dval, dval, dval, dval, uival, uival);minprintf("%%X=%X, %%u=%u, %%c=%c, %%p=%p, %%%%=%%\n", uival, uival, cval, pval);printf("%%X=%X, %%u=%u, %%c=%c, %%p=%p, %%%%=%%\n", uival, uival, cval, pval);
}/* minimal printf with variable argument list */
void minprintf(char *fmt, ...)
{/* points to each unnamed arg in turn */ va_list ap; char *p, *sval, format[3] = { '%', '\0', '\0' };int ival;double dval;unsigned int uival;void *pval;/* make ap point to 1st unnamed arg */ va_start(ap, fmt); for (p = fmt; *p; p++){if (*p != '%'){putchar(*p);continue;}switch (*++p){case 'd': case 'i': case 'c': /* char is promoted to int when passed through '...' */ ival = va_arg(ap, int);format[1] = *p;printf(format, ival);break;case 'f': case 'e': case 'E': case 'g': case 'G':dval = va_arg(ap, double);format[1] = *p;printf(format, dval);break;case 's':for (sval = va_arg(ap, char *); *sval; sval++)putchar(*sval);break;case 'x': case 'X': case 'o': case 'u':uival = va_arg(ap,<