(1)ループ出口と変数の振る舞いを問う
int main()
{
    int a,b=0;
    for (a=1;a<4;a++) {
        b=b+a;
        printf("a,b=%d %d\n",a,b);
    }
    while (b<12) {
        printf("a,b=%d %d\n",a,b);
        b=b+a+1;
        a++;
    }
    printf("a,b=%d %d\n",a,b);
}

(2)3ケタの数を作っているつもりの関数
関数内変数の独立性を問う
int func3(int x2, int x1, int x0)
{
    x2 = x2 * 100;
    x1 = x1 * 10;
    printf("B %d %d %d\n",x2,x1,x0);
    return x2+x1+x0;
}

int main()
{
    int x2=2, x1=7, x0=5, y;
    printf("A %d %d %d\n",x2,x1,x0);
    y=func3(x2,x1,x0);
    printf("C %d %d %d\n",x2,x1,x0);
    printf("y=%d\n",y);
}


(3)配列引数を問う
int func4(int x[], int size)
{
    int sss=0, i;
    sss=0;
    for (i=0; i<size; i++) {
        sss=sss+x[i];
    }
    return sss;
}



int main()
{
    int x[]={2,1,6,7,4,3};
    int z;
    z=func4(x,4);
    printf("z=%d\n",z);
    z=func4(x,6);
    printf("z=%d\n",z);
}



(4)文字列を逆順並び替えのつもり
void func51(char str[])
{
    int i=0, j=0, end;
    char tmp;
    while (str[j]!='\0') j++;
    j--;
    end=j;
    for (i=0; i<=end; i++, j--) {
        tmp=str[i];
        str[i]=str[j];
        str[j]=tmp;
    }
    str[end]='\0';
}

void func52(char str[])
{
    int i=0, j=0;
    char tmp;
    while (str[j]!='\0') j++;
    j--;
    for (i=0; i<j-1; i++, j--) {
        tmp=str[i];
        str[i]=str[j];
        str[j]=tmp;
    }
}





int main()
{
    char string1[32]="Twelve";
    char string2[32]="Nvember";
    printf("string1=%s\n",string1);
    printf("string2=%s\n",string2);
    func51(string1);
    func52(string2);
    printf("string1=%s\n",string1);
    printf("string2=%s\n",string2);
    func52(string2);
    printf("string2=%s\n",string2);
}



(5)文字列中から「+」を取り除くつもり
void func61(char s[],char d[])
{
    int i=0, k=0;
    while (s[i]!='\0') {
        if (s[i]!='+') {
            d[k]=s[i];
            k++;
        }
        i++;
    }
}

void func62(char s[],char d[])
{
    int i=0, k=0;
    while (s[i]!='\0') {
        if (s[i]!='+') {
            d[k]=s[i];
        } else {
            d[k]='#';
        }
        i++;
        k++;
    }
    d[k-1]='\0';
}



int main()
{
    char st1[32]="This+is+the+text.";
    char st2[32]="12345678901234567890";
    char st3[32]="12345678901234567890";
    printf("st1=%s\n",st1);
    printf("st2=%s\n",st2);
    func61(st1,st2);
    printf("st1=%s\n",st1);
    printf("st2=%s\n",st2);
    printf("st1=%s\n",st1);
    printf("st3=%s\n",st3);
    func62(st1,st3);
    printf("st1=%s\n",st1);
    printf("st3=%s\n",st3);
}

(6)文字列の一致を検査する
int cmpfunc1(char s1[], char s2[])
{
    int i=0;
    int equ=1;
    while (s1[i]!='\0' && equ==1) {
        if (s1[i]!=s2[i]) equ=0;
        i++;
    }
    return equ;
}

int cmpfunc2(char s1[], char s2[])
{
    int i=-1;
    int equ=1;
    do {
        i++;
        if (s1[i]!=s2[i]) equ=0;
    } while (s1[i]!='\0' && equ==1);
    return equ;
}

int main()
{
    char t0[]="abc";
    char t1[]="abc";
    char t2[]="abx";
    char t3[]="ab";
    char t4[]="abcd";
    int r1,r2;
    r1=cmpfunc1(t0,t1);
    r2=cmpfunc2(t0,t1);
    printf("%s %s %d %d\n",t0,t1,r1,r2);
    r1=cmpfunc1(t0,t2);
    r2=cmpfunc2(t0,t2);
    printf("%s %s %d %d\n",t0,t2,r1,r2);
    r1=cmpfunc1(t0,t3);
    r2=cmpfunc2(t0,t3);
    printf("%s %s %d %d\n",t0,t3,r1,r2);
    r1=cmpfunc1(t0,t4);
    r2=cmpfunc2(t0,t4);
    printf("%s %s %d %d\n",t0,t4,r1,r2);
    return 0;
}