How do nested loops execute in C?

"Recall that you can write loops within loops. The inner loop will execute fully for each iteration of the outer loop. An example of two nested of loops in C can be found in Code Sample 17.7.\n\n1 int i, j;\n\n2 int n = 10;\n\n3 int m = 20;\n\n4 for(i=0; i<n; i++) {\n\n5 for(j=0; j<m; j++) {\n\n6 printf(\"(i, j) = (%d, %d)\n\n\", i, j);\n\n7 }\n\n8 }\n\nCode Sample 17.7.: Nested For Loops in C\n\nThe inner loop executes for j = 0, 1, 2, . . . , 19 < m = 20 for a total of 20 iterations. However, it executes 20 times for each iteration of the outer loop. Since the outer loop executes for i = 0, 1, 2, . . . , 9 < n = 10, the total number of times the printf() statement execute is 10 × 20 = 200. In this example, the sequence (0, 0), (0, 1), (0, 2), . . . , (0, 19), (1, 0), . . . , (9, 19) will be printed."