2.2 #include main() { float x=2.5,y=2.5,z=2.5; printf("x=%f\n",x); printf("y=%f\n",y); printf("z=%f\n",z); } 3.1(1) #include main() { int a=12,b=3; float x=18.5,y=4.6; printf("%d\n",(float)(a*b)/2); printf("%d\n",(int)x%(int)y); } 3.2 #include main() { int x,b0,b1,b2,s; printf("Inputx:"); scanf("%d",&x); b2=x/100; b1=(x-b2*100)/10; b0=x%10; s=b0*100+b1*10+b2; printf("s=%d\n",s); } 3.3 #include #include main() { float rate=0.0225; float n,capital,deposit; printf("Input n,capital:"); scanf("%f,%f",&n,&capital); deposit=capital*pow(1+rate,n); printf("deposit=%f\n",deposit); } 3.4 #include #include main() { float a,b,c; double x,y; printf("Inputa,b,c:"); scanf("%f,%f,%f",&a,&b,&c); x=(-b+sqrt(b*b-4*a*c))/(2*a); y=(-b-sqrt(b*b-4*a*c))/(2*a); printf("x=%f,y=%f\n",x,y); } 4.1(1) #include main() { char c1='a',c2='b',c3='c'; printf("a%cb%cc%c\n",c1,c2,c3); } 4.1(2) #include main() { int a=12,b=15; printf("a=%d%%,b=%d%%\n",a,b); } 4.1(3) #include main() { int a,b; scanf("%2d%*2s%2d",&a,&b); printf("%d,%d\n",a,b); } 4.2 #include main() { long a,b; float x,y; scanf("%d,%d\n",&a,&b); scanf("%f,%f\n",&x,&y); printf("a=%d,b=%d\n",a,b); printf("x=%f,b=%f\n",x,y); } 5.1 #include main() { float a; printf("Innputa:"); scanf("%f",&a); if(a>=0) { a=a; printf("a=%f\n",a); } else { a=-a; printf("a=%f\n",a); } } 5.2 #include main() { int a; printf("Inputa:"); scanf("%d",&a); if(a%2==0) { printf("a 是偶数"); } else { printf("a 是奇数"); } } 5.3 #include #include main() { float a,b,c,s,area; printf("Inputa,b,c:"); scanf("%f,%f,%f",&a,&b,&c); if(a+b>c&&a+c>b&&b+c>a) { s=(a+b+c)/2; area=(float)sqrt(s*(s-a)*(s-b)*(s-c)); printf("area=%f\n",area); } else { printf("不是三角形"); } } 5.4 #include...