Fourth time assignment

First, the contents of the experiment

1, the experimental requirements: Write a program, enter an integer x, according to the output of the corresponding Y value.

Code:

#include <stdio.h>intMain () {inti,x,y=0; printf ("Please enter the value of x: \ n"); scanf ("%d",&x); if(x<1) {printf ("error:\n"); }    Else    {        if(%2!=0)        {             for(i=1; i<=x;i+=2) {y=y+i; }        }        Else        {             for(i=2; i<=x;i+=2) {y=y+i; }}} printf ("y=%d", y); return 0;}

Program Run Result:

2, the experiment request: The programming asks 1-1/2+1/3-1/4+1/5-... +1/99-1/100, the result retains two decimal places.

Code:

#include <stdio.h>intMain () {intx; floatA=1, y; Y=0;  for(x=1; x<= -; x + +)    {        if(%2==1) {y=y+a/x; }        Else{y=y-a/x; }} printf ("%.2f:\n", y); return 0;}

Program Run Result:

3, the experiment Request: output 2000 to 3000 all leap year's era name, each output 10 era name to change one line. Finally count the total number of leap years.

Code:

#include <stdio.h>intMain () {intb; b=0;  for(a= -; a<= the; a++)    {        if(a%4==0&&a% -!=0|| a% -==0) {printf ("%5d", a); b=b+1; if(b%Ten==0) {printf ("\ n"); }}} printf ("there are%d leap years in total", B); return 0;}

Program Run Result:

4, the experiment requires: Enter a real number x and an integer m, calculate XM, not allowed to call the POW () function.

Code:

#include <stdio.h>intMain () {floatx,y=1; intM,i; printf ("Please enter an integer and a real number: \ n"); scanf ("%d%f",&m,&x);  for(i=1; i<=m;i++) {y=y*x; } printf ("%f", y); return 0;}

Program Run Result:

5, the experiment requires: Enter a string of characters, respectively, the number of letters, spaces, numbers and other characters.

Code:

#include <stdio.h>intMain () {intN1,n2,n3,n4; CharC; N1=0; N2=0; N3=0; N4=0; printf ("Please enter a string of characters: \ n");  while((C=getchar ())! ='\ n')    {        if(c<='Z'&&c>='a'|| c<='Z'&&c>='A') {N1++; }        Else if(c==' ') {n2++; }        Else if(c>='0'&&c<='9') {N3++; }        Else{N4++; }} printf ("Letter =%d, Space =%d, digital =%d, other =%d", N1,N2,N3,N4); return 0;}

Program Run Result:

6, the experiment requires: Enter a number of numbers (positive and negative), enter 0 end, calculate the average of the positive and negative values, respectively,

Code:

#include <stdio.h>intMain () {intx,n1=0, n2=0; floatsum1=0, sum2=0; scanf ("%d",&x);  while(x!=0)    {        if(x>0) {sum1=sum1+x; N1++; }        Else if(x<0) {sum2=sum2+x; N2++; } scanf ("%d",&x); } printf ("positive average:%.2f negative mean:%.2f", sum1/n1,sum2/n2); return 0;}

Program Run Result:

7, the experimental requirements: output 1000 of all primes, 10 per line, and finally output a total number of prime numbers. (aligned per column)

Code:

#include <stdio.h>#include<math.h>intMain () {intn=0, I,x,y,z;  for(i=2; i<= +; i++) {y=1; Z=sqrt (i);  for(x=2; x<=z;x++)        {            if(i%x==0) {y=0;  Break; }        }        if(y==1) {n++; if(n%Ten==0) {printf ("\ n"); }            Else{printf ("%4d", i); }        }    }    return 0;}

The results of the program run:

8. Experimental requirements: Print the following graphic

Code:

#include <stdio.h>intMain () {inti,j;  for(i=1; i<=5; i++)    {         for(j=1; j<=i-1; j + +) printf (" ");  for(j=1; j<= One-2*i;j++) printf ("*"); printf ("\ n"); }    return 0;}

Program Run Result:

Ii. Summary of knowledge points in this course

1. For (the cyclic variable assigns the initial value; the cyclic condition; the cyclic variable adds value)

{Circular Body Statement}① semicolon cannot be omitted; ② is applicable to cyclic problems known as cycles;

2. while (loop condition)

{The Loop body statement}① the loop body may not be executed once, and the ② loop body should have the action of making the value of the expression tend to be false, thus exiting the loop; ③ applies to cycles known to be controlled by a given condition

3. Do

{loop body statement;}

while (loop condition); ① loop body must be executed at least once

4. Break

① is generally used with an if in a looping statement; The ②break statement cannot be used in a loop statement or in any other statement other than the switch statement;

5, continue

Used in conjunction with if, can only be used in the loop statement;

Iii. Summary of the experiment

1, pay attention to the writing of semi-colon, do...while sentence in the following need to add a semicolon;

2, the open square root expression is sqrt ();

3, judge whether the expression of the character is ((C=getchar ())! = ' \ n ');

4. In the loop body, printf does not need to enlarge brackets;

5, pay attention to the conditions of each cycle statement trial.

Fourth time assignment