#include <stdio.h>


int b;
int main()
{
int a, c;
printf("Enter the number of students \n");
scanf("%d", &a);

struct studinfo{
    char name[50];
    int roll;
    float marks;
};

struct studinfo s[10];

for(int i = 0; i <= a; i++)
{
    printf("Enter the Name :\n");
    scanf("%[^\n]s", s[i].name);      //THIS ONE HERE
    printf("\n");
    printf("Enter the roll no. \n");
    scanf("%d", &s[i].roll);
    printf("\n");
    printf("Enter the marks\n");
    scanf("%f", &s[i].marks);
}

for(int i = 0; i<= a; i++)
{
        printf("Name: %s\n", s[i].name);
        printf("Roll no: %d\n", s[i].roll);
        printf("Marks: %f", s[i].marks);
}
return 0;
}

Works when I remove the scanf to enter number of students. 

#包括

int b； int main（）{int a，c；printf（"输入学生人数\n"）；

struct studinfo{
    char name[50];
    int roll;
    float marks;
};

struct studinfo s[10];

for(int i = 0; i <= a; i++)
{
    printf("Enter the Name :\n");
    scanf("%[^\n]s", s[i].name);
    printf("\n");
    printf("Enter the roll no. \n");
    scanf("%d", &s[i].roll);
    printf("\n");
    printf("Enter the marks\n");
    scanf("%f", &s[i].marks);
}

for(int i = 0; i<= a; i++)
{
        printf("Name: %s\n", s[i].name);
        printf("Roll no: %d\n", s[i].roll);
        printf("Marks: %f", s[i].marks);
}
return 0;

}

-> This happenes because the Scanf initially used takes everything except for '\n' which is later is read by the next scanf which skips when it reads a '\n'.
-> Ive tried Fgets and gets too but still doesnt work.
- 

The output im getting is;

after I enter the number of students, it just skips the scanf to enter the name and just executes scanf to enter the roll no.