#include <stdio.h>
#include < stdlib.h>
void main()
{
int x = 30 ;
printf (" x = %d",x);
{
int x = 77;
printf (" x = %d",x);
}
while(x++ < 33)
{
int x = 100;
x++;
printf (" x = %d",x);
}
printf (" x = %d",x);
system("pause");
}
关于c99 代码块的新规则
#include <stdio.h>
#include <stdlib.h>
void main()
{
int n =10;
printf("Initially n = %d \n",n);
for (int n = 1; n < 3; n++)
{
printf("Loop n = %d \n",n);
}
printf("After loop n = %d \n",n);
for (int n = 1; n < 3 ; n ++) {
printf("Loop n = %d \n",n);
int n = 30 ;
printf("Loop n = %d \n",n);
n++;
}
printf("Loop n = %d \n",n);
system("pause");
}
使用 局部静态变量
#include <stdio.h>
#include <stdlib.h>
void srystat( void );
void main()
{
int count ;
for (count = 1 ; count <= 3 ; count++) {
printf("Here comes iteration %d \n ",count);
srystat();
}
system("pause");
}
void srystat(void )
{
int fade = 1;
static int stay = 1;
printf("fade = %d stay = %d ",fade ++ ,stay++);
}
外部函数 extern
使用外部变量
#include <stdio.h>
#include <stdlib.h>
int units = 0;
void critic(void);
void main()
{
extern int units;
printf("how many pound to a firkin of butter \n");
scanf("%d",&units);
while (units != 56) {
critic();
printf("your must have looked it up \n");
}
}
void critic()
{
printf("no luck chummy try again \n");
scanf("%d",&units);
}
各种存储类
#include <stdio.h>
#include <stdlib.h>
void report_count ();
void accumulate (int );
int count = 0;
void main()
{
int value ;
register int i;
printf("enter a positive interger 0 to quit ");
while (scanf("%d",&value) == 1 && value > 0) {
++count;
for(i = value; i >=0 ; i--) {
accumulate(i);
printf("enter a positive interger 0 to quit ");
}
report_count();
}
}
void report_count ()
{
printf("Loop executed %d time \n ",count);
}
#include <stdio.h>
#include <stdlib.h>
void report_count ();
static int total = 0;
int count = 0;
void accumulate (int k)
{
static int subtotal = 0;
if (k <= 0) {
printf("loop cycle %d \n",count );
printf("subtotal ; %d tpta; %d \n ",subtotal , total);
subtotal =0;
}
else
{
subtotal += k ;
total += k;
};
}
void main()
{
int value ;
register int i;
printf("enter a positive interger 0 to quit ");
while (scanf("%d",&value) == 1 && value > 0) {
++count;
for(i = value; i >=0 ; i--) {
accumulate(i);
}printf("enter a positive interger 0 to quit ");
report_count();
}
}
void report_count ()
{
printf("loop %d ",count);
}
#include <stdio.h>
#include <stdlib.h>
extern int rand0 (void);
int main()
{
int count ;
for (count = 0 ; count < 5 ; count ++) {
printf("%hd\n");
}
}
随机数种子
#include <stdio.h>
#include <stdlib.h>
static unsigned long int next = 1;
int rand0 (void);
void srand1 (unsigned int x);
int rand1 (void);
int rand1 (void)
{
next = next * 1103515245 + 12345;
return (unsigned int ) (next / 65535 )% 32767;
}
void srand1( unsigned int seed)
{
next = seed;
}
int main()
{
int count ;
unsigned seed;
printf("please enter your choice for seed \n");
while ( scanf("%u", &seed ) == 1 ) {
srand(seed);
for (count = 0 ; count < 5 ; count ++) {
printf("%hd\n",rand1());
}
printf("please enter your choice for seed \n");
}
for (count = 0 ; count < 5 ; count ++) {
printf("%hd\n");
}
}
#include <stdio.h>
#include <stdlib.h>
#include "Header.h"
int roll_count= 0;
void main()
{
rollem(10);
roll_n_dice(10, 11);
}
static int rollem (int sides)
{
int roll;
roll = rand() % sides +1;
++roll_count;
return roll;
}
int roll_n_dice(int dice,int sides)
{
int d;
int total = 0;
if (sides < 2) {
printf("Need at least 2 sides .\n");
return -2;
}
if (dice< 1 ) {
printf("Need at least 1 sides .\n");
return -1;
}
for (d = 0 ; d < dice ; d++) {
total += rollem(sides)
;
}
return total;
}
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include "Header.h"
void main()
{
int dice , roll;
int sides;
srand((unsigned int) time(0) );
printf("enter the number of sides per die 0 to stop \n");
while (scanf("%d",&sides) ==1 && sides > 0 )
{
printf("How\n");
scanf("%d",&dice);
roll =roll_n_dice(dice, sides);
printf("you have rolled a %d using %d %d -sided dice .\n",roll,dice,sides);
}
printf("the rollem () runction was called %d time ",roll_count);
}
malloc
#include <stdio.h>
#include <stdlib.h>
void main()
{
double * ptd;
int max;
int number;
int i = 0;
puts("what ,is the maxmum number of type double entries \n");
scanf("%d",&max);
ptd = (double *)malloc(max * sizeof(double));
if (ptd == NULL) {
puts("mem alll file ");
exit(EXIT_FAILURE);
}
puts("enter the values q to quit \n");
while (i < max && scanf("%lf",&ptd[i])) {//
++i;
}
printf("here are your %d entries \n ",number = i);
for (i = 0 ; i < number ; i++) {
printf("%7.2f",ptd[i]);
if (i % 7 ==6 ) {
putchar('\n');
}
}
if (i%7 != 0) {
putchar('\n');
}
puts("done");
free(ptd);
}
ANSI使用标准io
#include <stdio.h>
#include <stdlib.h>
int main(int argc ,char *argv[])
{
int ch ;
FILE *fp ;
long count = 0;
if (argc != 2 ) {
printf("Usae : %s filename \n",argv[0]);
exit(1);
}
if ((fp = fopen(argv[1], "r")) == NULL) {
printf("Can't open %s \n ",argv[1] );
exit(1);
}
while ((ch = getc(fp)) != EOF) {
putc(ch,stdout);
count++;
}
fclose(fp);
printf("File %s has %ld characters \n ",argv[1] , count);
return 0;
}
